Disorders of Carbohydrate Metabolism Flashcards
Lactose intolerance
- Lactase hydrolyzes lactose to glucose and galactose
- Deficiency of lactase
- lactose accumulates in the gut.
- Irritant diarrhea and flatulence
- congenital or acquired.
- Acquired lactose intolerance when there is a sudden
change to a milk based diet. - Curd treatment, because lactobacilli contains lactase.
Carrier protein defective in glucose-galactose malabsorption
SGluT-1
Carrier protein defective in congenital renal glycosuria
SGluT-2
A newborn baby had severe abdominal distension, severe abdominal pain, and diarrhea after being fed breast milk. Urine analysis revealed the presence of
reducing sugar. What is the possible defect? What is the confirmatory diagnostic test? How can it be treated?
- Lactose intolerance
- Symptoms due to undigested lactose causing its fermentation
- Lactose excreted in urine giving positive Benedicts test
- Confirmed by stool acidity test (lactic acid)
- Lactose free/soy milk, lactase tablets
Type 1 glycogen storage disease
Von Gierke’s
- Glucose 6 phosphotase
- Glucose 6 P accumulated, sent to HMP producing more ribose and purine nucl.
1. Fasting hypoglycemia that does not respond to adrenaline
2. Hyperlipidemia
3. Lactic acidosis, ketosis
4. Hyperuricemia
5. Liver enlargement and cirrhosis due to glycogen deposits
6. Children die early
Rx: little food at frequent intervals
Type 2 glycogen storage disease
Pompe's - a 1,4 glucosidase 1. Accumulation of glycogen in lysosomes of heart, liver, muscle 2. Infantile form: Death before 2 yrs Juvenile: Myopathy Adult: Muscular dystrophy
Type 3 glycogen storage disease
Cori’s
- a 1,6 glucosidase
- symptoms disappear at puberty
1. Branched dextrin accumulates
2. Fasting hypoglycemia
3. Hepatomegaly
4. Myopathy
Type 4 glycogen storage disease
Anderson’s
- branching enzyme
- glycogen with few branches
- liver failure may be due to immune rxn against abnormal glycogen
1. Hepatosplenomegaly
2. Cirrhosis
3. Cardiac, liver failure before 5yo
Type 5 glycogen storage disease
McArdle’s
- muscle glycogen phosphorylase
1. Exercise intolerance
2. Accumulation of glycogen in muscles
3. Myoglobinuria
Type 6 glycogen storage disease
Her’s
- Liver glycogen phosphorylase
1. Mild hypoglycemia
2. hepatomegaly
3. hyperlipidemia
4. ketosis
Type 7 glycogen storage disease
Tarui’s
- phosphofructokinase of muscle and RBC
1. Exercise intolerance
2. Haemolytic anaemia
G6PD deficiency
- X linked recessive
- only manifested on administration of antimalarial drug (primaquine), sulpha drugs or fava beans
- primaquine stimulates peroxide formation inside RBC
- as NADPH is low, this leads to lysis
- drug-induced haemolytic anaemia
- inc. met-Hb in circulation
- offers resistance to plasmodium infection
Bridges Good syndrome
Chronic Granulomatous Disease
- defect in NADPH oxidase system
- increased risk for infections like pneumonia, skin abcesses, osteomyelitis
Essential pentosuria
- one of Garrod’s tetrad
- inborn error
- absence of xylitol dehydrogenase/xylulose reductase
- L xylulose excreted in urine - positive Benedict
- Barbiturates, aminopyrine inc. xylulosuria
A 2-year-old child presented with liver enlargement. On investigation, Blood sugar–50 mg%, Uric acid–10 mg%, lactic acid–15 mg% and ketone bodies were present. Plasma cholesterol–300 mg%. What is the likely diagnosis? What is the biochemical basis of the disorder and its treatment?
Von Gierkes Hypoglycemia Hyperlactitemia Metabolic acidosis Hyperlipidemia Hyperuricemia Rx: maintain normoglycemia
A 6-year-old boy presented with general weakness. There was paleness, fatigue, shortness of breath and a rapid heart rate. History revealed that he had prolonged neonatal jaundice. Results at that time were as follows—Total Bilirubin— 10.0 mg%, Conjugated bilirubin—1.5 mg%, Unconjugated bilirubin—8.5 mg%. AST—30.0 U/L, ALT—35.0 U/L, ALP
—10.0 KAU/L. LDH—1000 U/L. Jaundice was triggered
on many occasions by bacterial and viral infections as well as some antibiotics. What is the likely diagnosis?
GPD deficiency.
-Jaundice is hemolytic in type
- kernicterus and anemia are present.
- Liver enzymes are normal
- lactate dehydrogenase levels are very high.
- Hemolytic anemia in GPD deficiency is triggered
by bacterial and viral infections.
A 3-year-old child was brought to the pediatrician for
complaints of fever and cough. On examination, all
systems were normal and no evidence for any genetic
disorder. On the safer side, the doctor performed urine screening to rule out an inborn error of metabolism. Benedict’s test result came as positive! Blood glucose—100 mg%, urine was negative for glucose as well as galactose; Bial’s test was positive. What is the likely diagnosis? What is the biochemical basis for this?
Essential pentosuria
Hereditary Fructose Intolerance
- autosomal recessive
- defect in aldolase B
- seen when sucrose is introduced in diet of infants
- accumulation of fructose 1 phosphate
- this inhibits glycogen phosphorylase
- this causes accumulation of glycogen in liver
- hypoglycemia
1. Vomiting
2. Loss of appetite
3. Hepatomegaly
4. Jaundice
5. Fructosuria - Benedict test positive
Fructosuria
- deficiency of fructokinase
- fructose in urine
- positive Benedicts and Seliwanoffs test
Galactosemia
- galactose 1 phosphate uridyl transferase def.
- galactose 1 phosphate accumulates in liver
1. Hypoglycemia - unconjugated bilirubin inc.
2. Jaundice
3. mental retardation
4. Liver enlargement
5. Galactosuria - Galactose converts into dulcitol in lens
6. Cataract - Galactose 1 phosphate gets accumulated in kidneys
7. amino aciduria
Rx: Lactose free diet
Leukocyte Adhesion Deficiency
- mutation affecting Golgi fucose transporter
- selectins not correctly glycosylated
- sluggish activity of leukocytes
Paroxysmal Nocturnal Haemoglobinuria
- somatic mutation in phosphatidyl inositol glycan gene in haemopoetic cells
- GPI linked proteins def. in RBC
- drop in pH of blood during sleep
- causes RBC lysis
- excretion of Hb
Common features of mucopolysaccharidoses
- excess intralysosomal accumulation of GAG
- progressive symptoms
- autosomal recessive
1. Coarse facial features
2. Thick skin
3. Corneal opacity
4. MR due to defective degradation of heparan sulphate
5. Growth def.
Mucopolysaccharidoses mnemonic
Hungry Hermione Stole Mangoes, Shrimp and Mushrooms Slyly
- Hurler’s
- Hunter’s
- Sanfillipos
- Morquio’s
- Scheie’s
- Maroteaux-Lamy’s
- Sly’s
Hurlers
L - iduronidase
- skeletal deformity
- corneal opacity
- DS HS in urine
Hunters
Iduronate sulfatase
- MR
- Skeletal deformity
- DEAFNESS
- DS HS in urine
Sanfillipos
Heparan sulphatase
- MR
- Skeletal deformity
- Corneal clouding
- HS in urine
Moriquos
Galactosamine sulfatase
- MR
- skeletal deformity
- corneal opacity
- EPIPHYSEAL DYSPLASIA
- KS CS in urine
Scheies
L- Iduronidase
- Mild skeletal deformity
- Corneal opacity
- DS
Maroteaux-Lamys
Galactosaminosulfatase
- Skeletal deformity
- Corneal opacity
- DS
Slys
Guluronidase
- MR
- DS HS
A 2-year-old child presented with liver enlargement.
Investigations showed the following results: Blood sugar –
50 mg%, Uric acid – 10 mg%, Lactic acid – 15mg%, Plasma
cholesterol – 300 mg% and ketone bodies were present.
Galactosemia
Hypoglcemia -> inc. fatty acid catabolism -> inc. Acetyl CoA -> sythesis of cholesterol and ketones
A 3-year-old boy is brought to the emergency department
after several episodes of vomiting and lethargy. His
pediatrician has been concerned about his failure to thrive
and possible hepatic failure along with recurrent episodes
of the vomiting and lethargy. After a careful history is
taken, it is found that these episodes occur after ingestion
of certain types of food, especially high in fructose. His
blood sugar was checked in the emergency department and
was extremely low.
Fructose intolerance
A 10-year-old child was brought to the OP Department with of constant dribbling of thick mucus from mouth
and not responding to surroundings. Clinical history
delayed developmental milestones since 2 years of age. The has coarse facial features and thick mucus and skeletal deformities. Urinalysis revealed presence of HS and DS
Hurlers syndrome
