Glycogen storage disease

1) Disease Description (Causes and Symptoms)

• Definition summary: Glycogen storage disease (especially GSD type I / Von Gierke disease) is an inherited carbohydrate metabolism disorder in which defects in the steps that break down glycogen into glucose in the liver, kidneys, and other organs cause problems maintaining glucose homeostasis. In Korea, GSD Ia (glucose-6-phosphatase deficiency) is the most common type.
• Cause/inheritance: Primarily autosomal recessive inheritance. GSD Ia is caused by glucose-6-phosphatase (G6PC) deficiency (gene location: the long arm of chromosome 17). Genetic testing can diagnose various mutations.
• Pathophysiology summary: Because G6P cannot be converted into glucose, G6P accumulates, and excessive glycogen is stored in the liver, kidneys, and other organs. The accumulated G6P flows into glycolysis, causing increased lactate (lactic acidemia), enters the purine metabolic pathway, causing increased uric acid, and increases lipid synthesis, causing hyperlipidemia.
• Main symptoms (early and progressive): Recurrent fasting hypoglycemia (with possible seizures), enlargement of the liver and kidneys (abdominal distension), growth delay/short stature, hyperlactatemia (increased lactate), hyperuricemia, hyperlipidemia, bleeding tendency, and a characteristic doll-like face. In the long term, there is a risk of developing liver tumors (possible hepatic adenoma/hepatocellular carcinoma), decreased kidney function, osteoporosis, and other conditions.

2) Treatment Methods and Precautions

• Basic treatment (standard):
  • Continuous nutritional support to prevent hypoglycemia and stabilize blood glucose is essential.
  • Uncooked cornstarch is used to maintain blood glucose overnight and during fasting: an example of the recommended dose is approximately 2 g/kg in a 50% solution every 6 hours (adjust according to the patient's condition). (Follow the clinician's instructions.)
  • Restrict fructose and lactose/galactose: these monosaccharides may worsen lactate and lipid production during metabolism.
  • For hyperuricemia, consider using a uric acid synthesis inhibitor (e.g., allopurinol).
• Medications, procedures, and surgery:
  • Symptom-control-focused drug treatment (individual treatment for hyperlipidemia, hyperuricemia, etc.).
  • Consider liver transplantation in cases of liver tumors, recurrent growth impairment, or inadequate metabolic control (liver transplantation restores metabolic control, but discuss long-term complications and indications with a specialist).
  • Portal shunt surgeries such as portacaval shunt surgery, which were performed in the past, are not currently standard treatment.
• Monitoring and lifestyle management:
  • Regular testing of blood glucose, lactate, uric acid, lipids, liver function, and kidney function (including urine protein, etc.).
  • Surveillance for liver tumors (imaging tests: ultrasound/CT/MRI) and, if necessary, biopsy and treatment.
  • Monitor growth and bone density (osteoporosis prevention).
  • Education: Recognize the symptoms of hypoglycemia and learn how to administer glucose in emergencies (oral/intravenous).
• Precautions (for self-management):
  • Avoid prolonged fasting; follow regular meals and snacks and the cornstarch administration schedule recommended by the doctor.
  • Limit alcohol and high-sugar foods (especially those containing fructose).
  • During stressful situations such as infection or surgery, a plan for blood glucose management is needed (discuss this with the medical team in advance).
• Complications (important): Liver tumors (hepatic adenoma → rarely malignant transformation), kidney failure, urinary stones and gout (hyperuricemia), growth impairment, osteoporosis, and metabolic problems (chronic complications).

3) Checklist Before an Outpatient Visit (Including Preparation Items and Example Questions)

• Items to bring (recommended for the visit):
  • A list of currently used medications and supplements (including the dose and interval of cornstarch administration)
  • Recent blood test results (blood glucose, lactate, uric acid, lipids, liver and kidney function, etc.) and imaging results (such as liver ultrasound)
  • Growth and weight charts (for children), and records of when hypoglycemia occurred and its symptoms
  • Records of emergency treatments used (e.g., injectable glucose)
• Information to provide to the doctor during the outpatient visit:
  • The frequency and circumstances of hypoglycemia (during fasting, after exercise, etc.)
  • Eating patterns and whether the cornstarch regimen has been followed
  • Any recent infection, surgery, or medication changes
• Example questions (prepared questions that patients or caregivers can ask the doctor):
  • "What do the recent blood test values (lactate, uric acid, lipids, etc.) mean?"
  • "How should the cornstarch dose and administration interval be adjusted?"
  • "What tests should be performed, and how often, to monitor for liver tumors?"

4) Examples of General Questions to Ask the Doctor

• What are the side effects and precautions for this medication (or a uric acid synthesis inhibitor, lipid-lowering medication, etc.)?
• Based on my current condition (test results), what is the prognosis? How high is the risk of long-term complications?
• What special precautions should be taken in daily life (exercise, school activities, travel)?
• If I am planning a pregnancy, what are the recommendations for genetic counseling or prenatal testing?

5) Examples of Disease-Specific Questions

• My (or my child's) hypoglycemia frequently occurs at night. How should the cornstarch dose and interval be adjusted? (Request recommendations by weight and age or blood glucose guidelines.)
• There are findings of a liver tumor (or liver enlargement). Please advise on the tumor surveillance interval and which imaging test is appropriate: ultrasound versus CT/MRI.

(Summary for reference) Main tests and diagnostic methods: Liver biopsy to confirm glycogen accumulation and enzyme activity, with G6PC genetic testing if necessary. Genetic characteristics: Usually autosomal recessive; prevalence is approximately 1 in 10,000–30,000 people (varies by region and ancestry). The key to treatment is continuous nutritional support (such as cornstarch) to prevent hypoglycemia, monitoring for complications, and individualized drug treatment.