Phenylketonuria : Causes-Symptoms-Diagnosis-Treatment

 What is Phenylketonuria (PKU)?

Phenylketonuria could be a genetic condition during which levels of essential amino acid build up within the blood. If it's not treated, PKU will cause brain injury and symptoms like seizures and heart defects. Treatment involves cutting short on supermolecules to limit the intake of essential amino acids.

Phenylketonuria (commonly referred to as PKU) is an Associate in Nursing genetic defect that will increase the amount of a substance known as essential amino acid within the blood. essential amino acid could be a building block of proteins (an amino acid) that's obtained through the diet. It's found altogether in proteins and in some artificial sweeteners. If PKU isn't treated, essential amino acids will build up to harmful levels within the body, inflicting intellectual incapacity and alternative serious health issues.

What is Phenylketonuria (PKU)?

The signs and symptoms of PKU vary from gentle to severe. The foremost severe style of this disorder is thought to be classic PKU. Infants with classic PKU seem traditional till they're many months previous. while not receiving treatment, these kids develop permanent intellectual incapacity. Seizures, delayed development, activity issues, and medical specialty disorders are common. Untreated people could have a musty or mouse-like odor as a result of excess essential amino acid within the body. Kids with classic PKU tend to possess lighter skin and hair than unaffected relations and are possible to possess skin disorders like skin disorder.

Less severe sorts of this condition, generally known as variant PKU and non-PKU hyperphenylalaninemia, have a smaller risk of brain injury. folks with terribly gentle cases might not need treatment with a low-phenylalanine diet.

Babies born to mothers WHO have PKU and uncontrolled essential amino acid levels (women WHO now not follow a low-phenylalanine diet) have a major risk of intellectual incapacity as a result of they're exposed to terribly high levels of essential amino acid before birth. These infants may have a coffee birth weight and grow a lot slower than alternative kids. alternative characteristic medical issues embrace heart defects or alternative heart issues, Associate in Nursing abnormally tiny head size (microcephaly), and activity issues. Girls with PKU Associate in Nursing uncontrolled essential amino acid levels even have an inflated risk of physiological state loss.

  1. Medical And Anatomical Concept Of The Human Body

Medical terms

  • Phenylketonuria (fen-ul-key-toe-NU-ree-uh), conjointly referred to as phenylketonuria, may be a rare hereditary disease that causes Associate in Nursing amino alkanoic acid referred to as essential amino acid to create up within the body. Phenylketonuria is caused by a defect within the sequence that helps produce the catalyst required to interrupt down essential amino acids.

  • Without the catalyst necessary to method essential amino acid, a dangerous buildup will develop once someone with phenylketonuria grub foods that contain supermolecule or grub sweetener, a man-made sweetener. This may eventually cause serious health issues.

  • For the remainder of their lives, individuals with phenylketonuria — babies, kids and adults — have to be compelled to follow a diet that limits essential amino acid, which is found largely in foods that contain supermolecules.

  • Babies within the u. s. and plenty of alternative countries square measure screened for phenylketonuria before long when birth. Recognizing phenylketonuria directly will facilitate forestall major health issues.

  • Phenylketonuria (PKU) is a genetic disorder that prevents the body from breaking down an amino acid known as phenylalanine Phenylalanine is found in many foods including meats eggs and dairy products When someone with PKU eats these foods the unbroken-down amino acid gets into the bloodstream causing levels of phenylalanine to rise abnormally high The excess phenylalanine alters the brain's chemistry and affects mental development For example it may cause developmental delays or intellectual disabilities If left untreated PKU can be fatal

  • Phenylketonuria or PKU is an inherited disorder which results in high levels of phenylalanine a naturally occurring amino acid in the blood In most infants with Phenylketonuria (PKU) the first sign of the disease is often a change in bowel movements - from regular to loose stools or very hard and dry stools The baby may also lose weight become irritable and have feeding problems Over time the untreated condition can lead to seizures delayed development mental retardation and other serious health problems.

Symptoms Phenylketonuria (PKU)

A child UN agency is born with PKU and isn't treated can have intellectual and organic process issues. He or she is going to even have less pigmentation within the skin.

People living with classic PKU (also known as severe PKU) and the UN agency don't seem to be on a metabolic diet or being treated have the subsequent symptoms. Newborns with PKU at first haven't got any symptoms. However, while not treated, babies sometimes develop signs of PKU at intervals a couple of months.

  • A musty odor in the breath, skin or urine, caused by too much phenylalanine in the body

  • Neurological problems that may include seizures

  • Skin rashes (eczema)

  • Fair skin and blue eyes, because phenylalanine can't transform into melanin — the pigment responsible for hair and skin tone

  • Abnormally small head (microcephaly)

  • Hyperactivity

  • Intellectual disability

  • Delayed development

  • Behavioral, emotional and social problems

  • Psychiatric disorders

Severity varies

The severity of PKU depends on the type.

  • Classic PKU. The most severe type of the disorder is named classic PKU. The catalyst required to convert essential amino acid is missing or severely reduced, leading to high levels of essential amino acid and severe brain injury. 

  • Less severe forms of PKU. In gentle or moderate forms, the accelerator retains some operation, thus essential amino acid levels don't seem to be as high, leading to a smaller risk of serious brain injury.
    But most kids with the disorder still need a special PKU diet to stop intellectual incapacity and alternative complications. 

Pregnancy and PKU

Women WHO have inborn error of metabolism and become pregnant are in danger of another sort of the condition referred to as maternal inborn error of metabolism. If ladies do not follow the special inborn error of metabolism diet before and through physiological state, blood essential amino acid levels will become high and damage the developing craniate or cause a miscarriage.

Even ladies with less severe varieties of inborn error of metabolism could place their unhatched youngsters in danger by not following the inborn error of metabolism diet.

Babies born to mothers with high essential amino acid levels do not typically inherit inborn error of metabolism. However, they'll have serious consequences if the extent of essential amino acid is high within the mother's blood throughout the physiological state. Complications at birth could include:

  • Low birth weight

  • Delayed development

  • Facial abnormalities

  • Abnormally small head

  • Heart defects and other heart problems

  • Intellectual disability

  • Behavioral problems

When to see a doctor

Seek medical advice in these situations:

  • Newborns. If routine newborn screening tests show that your baby could have phenylketonuria, your child's doctor may need to begin dietary treatment quickly to forestall long-run issues. 

  • Women of childbearing years. It's particularly necessary for girls with a history of inborn error of metabolism to visualize a doctor and maintain the inborn error of metabolism diet before turning into pregnant and through maternity to scale back the chance of high blood essential amino acid levels harming their unhatched babies. 

  • Adults. People with PKU continue to receive care across the life span. Adults with PKU who have stopped the PKU diet in their teens may benefit from a visit with their doctors. Returning to the diet may improve mental functioning and behavior and slow damage to the central nervous system that can result from high phenylalanine levels.

Causes Phenylketonuria (PKU)

Mutations within the PAH cistron cause inborn error of metabolism. The PAH cistron provides directions for creating associate degree catalysts referred to as essential amino acid hydroxylase. This catalyst converts the organic compound essential amino acid to alternative necessary compounds within the body. If cistron mutations cut back the activity of essential amino acid hydroxylase, essential amino acid from the diet isn't processed effectively. As a result, this organic compound will build up to noxious levels within the blood and alternative tissues. As a result of nerve cells within the brain square measure significantly sensitive to essential amino acid levels, excessive amounts of this substance will cause brain injury.

Classic inborn error of metabolism, the foremost severe kind of the disorder, happens once essential amino acid hydroxylase activity is severely reduced or absent. folks with untreated classic inborn error of metabolism have levels of essential amino acid high enough to cause severe brain injury and alternative serious health issues. Mutations within the PAH cistron that enable the catalyst to retain some activity lead to milder versions of this condition, like variant inborn error of metabolism or non-PKU hyperphenylalaninemia.

A defective cistron (genetic mutation) causes inborn error of metabolism, which may be gentle, moderate or severe. In an exceedingly person with inborn error of metabolism, this defective cistron causes an absence of or deficiency of the catalyst that is required to method essential amino acid, associate degree organic compound.

A dangerous buildup of essential amino acid will develop once an individual with inborn error of metabolism fare protein-rich foods, like milk, cheese, kooky or meat, and even grains like bread and alimentary paste, or fare sweetener, a synthetic sweetener. This buildup of essential amino acid leads to injury to nerve cells within the brain.


For a toddler to inherit phenylketonuria, each mother and father should have and die from the defective sequence. This pattern of inheritance is named chromosome recessive.

It's attainable for a parent to be a carrier — to possess the defective sequence that causes phenylketonuria, however not have the malady. If just one parent has the defective sequence, there is no risk of passing phenylketonuria to a toddler, however it's attainable for the kid to be a carrier.

Most often, phenylketonuria is passed to youngsters by 2 folks WHO are unit carriers of the disorder, however they do not know it.

Risk factors Phenylketonuria (PKU)

Risk factors for inheriting PKU include:

  • Having both parents with a defective gene that causes PKU. Two parents must pass along a copy of the defective gene for their child to develop the condition.

  • Being of certain ethnic descent. The gene defect that causes PKU varies by ethnic groups and it's less common in African-Americans than in other ethnic groups.

Complications Phenylketonuria

Untreated inborn error of metabolism will result in complications in infants, kids and adults with the disorder. Once mothers with inborn error of metabolism have high blood essential amino acid levels throughout their physiological state, vertebrate birth defects or miscarriage will occur.

Untreated inborn error of metabolism will lead to:

  • Irreversible brain damage and marked intellectual disability beginning within the first few months of life

  • Neurological problems such as seizures and tremors

  • Behavioral, emotional and social problems in older children and adults

  • Major health and developmental problems

How do you deal with PKU?

People with PKU need to eat a special diet. Children usually have their protein intake carefully controlled by a dietitian and their caregivers until they reach adulthood when they assume responsibility for following the diet themselves. The diet must be followed precisely to prevent health problems and mental retardation.

What is the life expectancy of a person with phenylketonuria?

With proper treatment and care a person with phenylketonuria can have a near normal life expectancy Many people with PA are diagnosed soon after birth and will take medications on a regular basis throughout their life to control the disease It is important that they keep in contact with their doctor because they need to adjust their medication as they get older The cause of death for most individuals with PA is usually associated with heart problems or seizure disorders.

Can PKU be corrected?

PKU has no cure at present and can not be treated; but the condition is completely manageable with diet and it can be effectively managed In order to manage PKU individuals have to strictly follow a low protein diet throughout their lives The daily intake of proteins must not exceed 5–6 grams If this limit is exceeded the urine becomes dark and unpleasant in odor plus it causes mental retardation which occurs when blood phenylalanine levels are elevated in the bloodstream for more than two weeks.

Why can PKU not be cured?

PKU is a genetic condition that affects the amino acid called phenylalanine (phe) and the ability of the body to break it down into other components Because of this people with PKU have too much phe in their blood Phe in large amounts is harmful to various organs including liver heart and brain A diet low in protein must be followed throughout life to control this disorder because no cure has been found yet.

Can you eat rice with PKU?

Phenylketonuria (PKU) a recessive genetic disorder of amino acid metabolism was first described in 1934 by two Dutch physicians Jan Vijg and Malda Mastenbroek This condition is marked by the inability to metabolize phenylalanine at the enzyme level PKU is one of the more common single gene disorders in humans affecting about 1 in 10 000 individuals worldwide What happens when people with Phenylketonuria (PKU) eat foods that contain large amounts of protein? Their blood levels of phenylalanine rise very quickly and they will begin to show symptoms such as.

What supplements do PKU patients take?

A PKU diet contains 100 g of protein each day It also must be very low in phenylalanine People with PKU are advised not to supplement their diet for fear of increasing the amount of phenylalanine that they ingest This means that if a person with PKU does not eat enough protein or does not ingest enough B vitamins the brain and nervous system can suffer damage on account of an insufficiency of these essential nutrients.

and management The treatment for phenylketonuria is to restrict the intake of phenylalanine This removes the chemical from the body and prevents it from accumulating in an excessive amount which can lead to adverse effects If a person has PKU then his or her dietitian and doctor will work together to create a specialized meal plan The dietitian will monitor your child's blood levels regularly while you are following this special meal plan Phenylketonuria Diet Plan: How It Works Your mealtime guidelines will depend on how severe your child’s PKU is Most children.

Prevention Phenylketonuria

If you have PKU and are considering getting pregnant:

  • Follow a low-phenylalanine diet. Women with PKU can prevent birth defects by sticking to or returning to a low-phenylalanine diet before becoming pregnant. If you have PKU, talk to your doctor before you start trying to conceive.

  • Consider genetic counseling. If you have got phenylketonuria, an in depth relative with phenylketonuria or a baby with phenylketonuria, you will conjointly like direction before turning into pregnant. A doctor UN agency focusing on medical biology (geneticist) will assist you in higher perception however phenylketonuria is more responsible for your kindred. He or she will be able to jointly verify your risk of getting a baby with phenylketonuria and assist with planning. 

Diagnosis Phenylketonuria (PKU)

PKU is diagnosed with a biopsy. Within the U.S. and most different countries, a biopsy is taken through a heel stick on newborn babies among forty eight hours of birth. more tests are needed to substantiate the sort of inborn error of metabolism and set up the simplest manner of treating it. In older individuals, inborn error of metabolism is diagnosed with a biopsy that measures levels of essential amino acid within the blood.

Newborn blood testing identifies most cases of PKU. All fifty states within the u. s. need newborns to be screened for inborn error of metabolism. several different countries conjointly habitually screen infants for inborn error of metabolism.

  1. prenatal testing

If you've got an inborn error of metabolism or a case history of it, your doctor might advocate screening tests before gestation or birth. It's doable to spot inborn error of metabolism carriers through a biopsy.

Testing your baby after birth

A PKU test is completed daily or 2 when your baby's birth. The check is completed when your baby is twenty four hours old and when your baby has eaten some macromolecule within the diet to make sure of the correct results.

  • A nurse or lab technician collects a few drops of blood from your baby's heel or the bend in your baby's arm.

  • A laboratory tests the blood sample for certain metabolic disorders, including PKU.

  • If you don't deliver your baby in a hospital or are discharged soon after the birth, you may need to schedule a newborn screening with your pediatrician or family doctor.

If this test indicates your baby may have PKU:

  • Your baby may have additional tests to confirm the diagnosis, including more blood tests and urine tests

  • You and your baby may have genetic testing to identify gene mutations

Treatment Phenylketonuria (PKU)

The main treatment for PKU includes:

  • A lifetime diet with very limited intake of protein, because foods with protein contain phenylalanine

  • Taking a phenylketonuria formula — a special nutritional supplement — always to form positive you get enough essential supermolecule (without phenylalanine) and nutrients that are crucial for growth and general health
    A safe quantity of essential amino acid differs for every person with phenylketonuria and might vary over time. In general, the concept is to consume solely the number of essential amino acids that is necessary for traditional growth and body processes, however not a lot of. Your doctor will verify a secure quantity through:

  • Regular review of diet records, growth charts and blood levels of phenylalanine

  • Frequent blood tests that monitor phenylalanine levels as they change over time, especially during childhood growth spurts and pregnancy

  • Other tests that assess growth, development and health

Your doctor may refer you to a registered dietitian who can help you learn about the PKU diet, make adjustments to your diet when needed, and offer suggestions on ways to manage PKU diet challenges.

Which foods to avoid

Because the amount of phenylalanine that a person with PKU can safely eat is so low, it's crucial to avoid all high-protein foods, such as:

  • Milk

  • Eggs

  • Cheese

  • Nuts

  • Soybeans

  • Beans

  • Chicken

  • Beef

  • Pork

  • Fish

Potatoes, grains and different vegetables that have supermolecule can doubtless be restricted.

Children and adults additionally got to avoid bound different foods and beverages, as well as several diet sodas and different drinks that contain sweetener (NutraSweet, Equal). Sweetener is a synthetic sweetener created with essential amino acids.

Some medications could contain sweetener and a few vitamins or different supplements could contain amino acids or milk powder. seek advice from your pill roller concerning the contents of over-the-counter merchandise or prescription medications.

Talk along with your doctor or registered nutritionist to find out a lot concerning your specific dietary desires.

Formula for people with PKU

Because of the restricted diet, folks with PKU got to get essential nutrients through a special organic process supplement. The phenylalanine-free typeula provides protein and different essential nutrients in an exceedingly form that is safe for folks with PKU.

Your doctor and nutritionist will assist you notice the proper style of formula.

  • Formula for babies and toddlers. Because regular kid formula and breast milk contain essential amino acid, babies with phenylketonuria instead ought to consume a phenylalanine-free kid formula. A dietician will rigorously calculate the quantity of breast milk or regular formula to side with the phenylalanine-free formula. Oldsters introduce solid foods with low levels of essential amino acid to kids with phenylketonuria on identical schedules used for different infants. 

  • Formula for older children and adults. Older kids and adults still drink or eat a supermolecule substitute formula daily, as directed by a doctor or specialist. Your daily dose of formula is split between your meals and snacks, rather than consumed all right away. The formula for older kids and adults isn't similar because the one used for infants, however it works on a similar principle. It provides essential supermolecules (amino acids) while not essential amino acids and is sustained always.
    The need for a biological process supplement, particularly if your kid does not notice it appealing, and therefore the restricted food selections will create the phenylketonuria diet difficult. However, families have to create a firm commitment to the present way of modification as a result solely thanks to forestall the intense health issues that individuals with phenylketonuria will develop. 

Neutral amino acid therapy

Another doable addition to the inborn error of metabolism diet may be a supplement known as neutral amino alkanoic acid medical care in powder or pill kind. This supplement could block some absorption of essential amino acids. This could be a treatment possibility for adults with inborn error of metabolism. raise your doctor or specialist if this supplement is suitable for your diet.

PKU medication

The Food and Drug Administration (FDA) has approved the drug sapropterin (Kuvan) for the treatment of phenylketonuria. It works by increasing your tolerance to essential amino acids. The drug is to be used together with a phenylketonuria diet. however it does not work for everybody with phenylketonuria.

In approving sapropterin, the authority directed that studies continue as a result of there aren't any semipermanent studies on the drug's effectiveness and semipermanent safety. 

Lifestyle and home remedies

Some strategies to help manage PKU may include the following.

Keep track and measure correctly

If you or your kid is following a low-phenylalanine diet, you will need to keep records of the food eaten on a daily basis to make sure you are protruding to the precise, personalized dietary pointers counseled by your nutritionist.

To be as correct as attainable, live food parts victimize normal measurement cups and spoons and a room scale that reads in grams. The food amounts square measure compared with a food list or square measure wont to calculate the quantity of essential amino acid eaten on a daily basis. Every meal and snack includes the befittingly divided portion of your daily PKU formula.

Food diaries or pc programs square measure are offered that list the quantity of essential amino acids in baby foods, solid foods, PKU formulas, and customary baking and change of state ingredients.

Buy low-protein products

To add selection to your diet, get a number of the various low-protein merchandise, like low-protein alimentary paste, rice, flour and bread, that are accessible through specialty food retailers.

These merchandise permit individuals with PKU to eat some meals that closely match what everybody else is intake. Just like the PKU formulas, these merchandise will be big-tickets, however you could possibly take into account splurging on some favorites with the money you save on farm and meat merchandise.

Be creative

Talk along with your specialiser to seek out however you'll be able to be inventive with foods to assist you continue track. For instance, use seasonings and a range of change of state ways to rework lower essential amino acid vegetables into an entire menu of various dishes. Herbs and flavorings low in essential amino acid will pack a tasteful punch. simply bear in mind to live and count each ingredient and alter recipes to your personalized diet.

If you have other health conditions, you'll additionally have to think about those once you arrange your diet. speak along with your doctor or specialiser if you have got any queries.

Coping and support

Living with PKU can be challenging. These strategies may help:

  • Stay informed. Knowing the facts concerning PKU will assist you take hold of things. Discuss any queries along with your pediatrician, general practitioner, biologist or dietician. browse books and cookbooks specifically written for individuals with PKU. 

  • Learn from other families. Ask your doctor concerning native or on-line support teams for individuals addressing inborn error of metabolism. Talking with others World Health Organization have down pat similar challenges will be terribly useful. The National inborn error of metabolism Alliance is a web support cluster for adults with inborn error of metabolism. 

  • Get help with menu planning. A registered dietitian with experience in PKU can help you devise delicious low-phenylalanine dinners. He or she may also have great ideas for holiday meals and birthdays.

  • Plan ahead when you eat out. A meal at the native edifice offers you a possibility from the room and may be fun for the complete family. Most places provide one thing that matches into the PKU diet. however you will need to decide ahead and raise the menu or bring food from home. 

  • Find sources of financial aid. Ask your doctor or dietician if there are square measure programs or insurance plans that facilitate the high prices of formula and low-protein foods. Also, see if your native college lunch program can accommodate special dietary wants. 

  • Don't focus on food. Encourage children with PKU to focus on sports, music or favorite hobbies, not on just what they can and can't eat. Also consider creating holiday traditions that center on special projects and activities, not just food.

  • Let your child help manage his or her diet as early as possible. Toddlers will build selections concerning that cereal, fruit or vegetable they'd wish to eat and facilitate making up one's mind parts. they will additionally facilitate themselves to pre-measured snacks. Older kids will facilitate the menu coming up with, pack their own lunches and keep their own food records. 

  • Make your grocery list and meals with the whole family in mind. A cupboard jam-packed with restricted foods is tempting to a baby or adult with phenylketonuria, therefore attempting to specialize in foods that everybody will eat. Serve stir-fried vegetables that are unit lower in supermolecule. If the opposite is true, they'll add peas, corn, meat and rice. Or started a bar with low-protein and moderate-protein choices. you'll be able to conjointly serve the complete family a delicious low-phenylalanine soup or curry. 

  • Be prepared for potlucks, picnics and car trips. Plan ahead, thus there is forever a PKU-friendly food choice. Pack dehydrated fruit snacks, raisins and lower macromolecule nutty for the automobile. Take fruit kebabs or vegetable skewers to a picnic, and create a low-phenylalanine dish for the neighborhood meal. different oldsters, friends and relations can seemingly be accommodating and useful if you justify the dietary restrictions. 

  • Talk to teachers and other staff in your child's school. Your child's academics and eating house employees is a giant problem with the inborn error of the metabolism diet if you're taking the time to clarify its importance and the way it works. By operating along with your child's academics, you'll additionally set up ahead for special college events and parties so your kid forever includes a treat to eat. 

  • Maintain a positive food attitude. When children know nothing but the foods they are given, they can be surprisingly accepting of the PKU diet — especially when their parents are positive problem-solvers.

Preparing for your appointment

Phenylketonuria is mostly diagnosed through newborn screening. Once your kid is diagnosed with inborn error of metabolism, you will probably be cited by a middle or specialty clinic with a doctor United Nations agency makes a specialty of treating inborn error of metabolism and a nutritionist expertly within the inborn error of metabolism diet.

Here's some data to assist you make preparations for your appointment and understand what to expect from your doctor.

What you can do

Before your appointment:

  • Ask a family member or friend to come with you — sometimes it can be difficult to remember all of the information provided during an appointment.

  • Make a list of questions to ask your doctor and dietitian to help you make the most of your time together.

Some basic questions to ask may include:

  • How did my child get PKU?

  • How can we manage PKU?

  • Are there any medications to treat this disease?

  • What foods are completely off-limits?

  • What is the recommended diet?

  • Will my child have to stay on this special diet for life?

  • What kind of formula will my child need? Can my child have breastmilk?

  • Are there any other supplements needed?

  • What happens if my child eats food that he or she is not supposed to eat?

  • If I have another child, will he or she have PKU?

  • Are there brochures or other printed material that I can have? What websites do you recommend?

What to expect from your doctor

Your doctor is likely to ask you several questions. Be ready to answer them to reserve time to go over points you want to focus on. For example, your doctor may ask:

  • Has your child had any symptoms that concern you?

  • Do you have any questions about your child's diet?

  • Are you having any difficulty following the diet?

  • Has the growth and development of your child been typical of other children the same age?

  • Have you ever had genetic testing?

  • Do any other relatives have PKU?

General summary

  1. There are no known treatments or cures for PKU However people with PKU can live long healthy and normal lives with careful diet management Avoiding all sources of phenylalanine from birth is the most effective way to manage the disorder In addition to their medical care team people with PKU should work closely with a registered dietitian who specializes in PKU to prepare balanced meals that meet each day's recommended allowance of protein vitamins and minerals.

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