Internal Medicine

0521779407-08 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:47

636 Glycogen Storage Disease

myoglobinuria (VII: Tarui disease from muscle phosphofruc-

tokinase deficiency)

Adult with weakness and poor exercise tolerance. May present

vaguely or with severe cramps and burgundy urine.

(V: McArdle disease from muscle phosphorylase deficiency)

Hypertrophic cardiomyopathy (Danon’s disease from X-linked

lysosome-associated membrane protein [LAMP2] deficiency)

(mutations in PRKAG2, the regulatory gamma subunit of AMP-

activated protein kinase)

➣Other findings

Short stature, gout, steatorrhea, epistaxis, bruising, xantho-

mas, pancreatitis, kidney stones, osteoporosis, hepatic adeno-

mas (I)

Bacterial infections, mucosal ulcerations, inflammatory bowel

disease (Ib: Von Gierke disease from translocase deficiency)

Weak muscles of respiration (II, III)

Splenomegaly (III)

Hemolysis (VII)

tests

Laboratory

■Basic Blood Studies

➣Blood genetic analyses (LAMP2, PRKAG2)

➣Fasting hypoglycemia with low insulin levels and ketosis

With normal lactate and uric acid (0, III, VI, IX)

With normal lactate and high uric acid (VII)

With high lactate and uric acid (I)

➣Elevated transaminases (III, IV, VI, IX)

Usually normal in type I

➣Elevated triglycerides (mild: III, VI, IX; severe: I)

➣Elevated CPK (II, IV, V, VII)

➣Renal insufficiency (I)

■Basic Urine Studies

➣May show Fanconi’s syndrome (I)

➣Myoglobinuria (V, VI, VII)

■Specific Diagnostic Tests

➣Lactate, free fatty acids, ketones and uric acid increase hourly

after an oral glucose load of 1.75 g/kg (I)

➣Minimal glucose response to IM or IV glucagon (30 mcg/kg, max-

imum 1 mg), while elevated lactate rises further (I)