Clinical Presentation Of Type 1 Glycogen Storage Disease

Type 1 glycogen storage disease, sometimes referred to as von Gierke disease, is a genetic disorder that affects the metabolism of a complex sugar known as glycogen. Patients with this condition experience a buildup of glycogen in the body that can impair the normal functioning of the liver, kidneys, and small intestines. Scientists have currently identified two types of this disorder: type 1A and type 1B. To diagnose type 1 glycogen storage disease, doctors will perform blood tests to measure glucose levels, lipids, and uric acid, and genetic testing may be performed to check for mutations on several genes. Ultrasound tests will also be conducted to examine the size of the liver and kidneys, and some patients might need to have a liver biopsy. Individuals with this condition are typically diagnosed between four and ten months old. Treatment options emphasize promoting infant growth and correcting the metabolic imbalances associated with the disorder. Parents of children with type 1 glycogen storage disease are encouraged to give their child frequent feedings in small amounts throughout the day. Doctors often advocate adding uncooked cornstarch to soy formula for infants with this disease; the cornstarch provides a slow and steady release of glucose. Some patients with type 1 glycogen storage disease may need to have overnight glucose feedings through a nasogastric tube. Patients might be advised to limit certain sugars in their diets too.

The symptoms described below are commonly seen in patients with type 1 glycogen storage disease.

Hepatomegaly

Hepatomegaly (an enlarged liver) occurs in patients with type 1 glycogen storage disease as excess glycogen accumulates in the organ. Affected individuals will tend to clinically present with an enlarged abdomen too. To assess the severity of hepatomegaly, the doctor will perform a clinical examination of the entire abdomen. They will palpate the patient's liver to assess for any pain or tenderness and estimate the size of the organ. CT scans and ultrasounds can confirm liver enlargement and provide detailed information about the severity of the enlargement and the presence of any scarring or other abnormalities. Occasionally, patients with type 1 glycogen storage disease may develop benign tumors on the liver; these are known as hepatic adenomas. Although rare, some patients might develop malignant liver tumors, so it is important for regular imaging studies to be performed. These imaging tests can also monitor the enlargement of the liver over time.

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Hypoglycemia

Hypoglycemia (low blood sugar) is a frequent concern for patients with type 1 glycogen storage disease, and most will have repeated or prolonged episodes of hypoglycemia. In infants, low blood sugar can lead to seizures. Patients struggling with low blood sugar will often be asked to track their glucose levels at home. To do so, they will need to use a lancet to obtain a drop of blood from the finger or forearm. The blood is then placed on a special testing paper and inserted into a glucometer, which will display a measurement of the blood sugar level. Depending on the severity of their symptoms, patients might be advised to check their blood sugar readings several times a day, particularly before and after meals and before bedtime. It can be helpful to keep a log of the readings that can be shown to physicians. To reduce hypoglycemia episodes, patients will need to eat small amounts of carbohydrates at regular intervals throughout the day, and this meal plan will need to be maintained for life. A nutritionist can help the patient with finding meal options that suit their lifestyle and health needs.

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Hyperlipidemia

Hyperlipidemia is a major symptom of type 1 glycogen storage disease, and it typically begins in infancy. Affected patients often display both elevated total cholesterol and elevated triglycerides. Simple blood tests are needed to evaluate cholesterol levels, and these can be performed at the doctor's office. Generally, patients will have to be placed on medication to lower cholesterol levels, and frequent blood tests might be necessary to plan the most effective cholesterol-lowering treatment.

For children, a normal total cholesterol reading is 170mg/dL or below; readings of between 170mg/dL and 199mg/dL are considered borderline, and anything above is classified as elevated. In adults, total cholesterol readings of less than 200mg/dL are categorized as optimal, and readings between 200mg/dL and 239mg/dL are borderline. Anything at or above 240mg/dL is categorized as high.

To reduce cholesterol levels, most patients with type 1 glycogen storage disease are started on prescription medications known as statins. These drugs work by suppressing the function of a liver enzyme that produces cholesterol. While taking statins and other cholesterol-lowering medications, patients should be aware of the potential side effects. In particular, statins may cause headaches, sleeping problems, abdominal pain, diarrhea, and muscle pain or weakness. Patients who experience any muscle pain should inform their physician immediately as this could sometimes be a sign of serious complications.

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Lactic Acidosis

Lactic acidosis is an accumulation of lactic acid in the body, and this symptom generally appears during infancy for individuals with type 1 glycogen storage disease. Patients experiencing lactic acidosis may have a decreased appetite, and they might develop muscle pain or cramps as well. Abdominal pain, fatigue, drowsiness, and weakness are frequently observed. In many cases, an accumulation of lactic acid is considered a medical emergency, and the patient should go to an emergency room for proper treatment. The standard course of treatment for excess lactic acid is to administer an intravenous infusion of sodium bicarbonate. Peritoneal dialysis with bicarbonate-based dialysate might be recommended as well.

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Growth Failure

Infants with type 1 glycogen storage disease often exhibit growth failure. In general, they will grow more slowly than their peers, and they are often shorter than their peers as well. Healthcare professionals will check a child's height and weight at each clinic appointment, and these results are plotted on a graph and classified in what is known as a growth percentile. This information can guide physicians in making nutrition recommendations. As patients with this condition grow up, they may have delayed puberty, and females with this disorder might experience abnormalities in the development of the ovaries. To help the patient grow as well as possible and maintain a normal weight, doctors recommend eating a high-carbohydrate diet with several small meals throughout the day. Some patients with the condition find it helpful to eat up to six small meals a day. When choosing carbohydrates and sugars, patients should focus on foods with glucose instead of fructose; these foods will also help in preventing low blood sugar.