Overdose of vitamin A mainly affects_____
Ans. c (Lysosome) (Ref OP Ghai Paediatrics 6th/121)OP Ghai Paediatrics 6th/121: Hypervitaminosis AExcess of vitamin A can lead to rupture of lysosomal membrane. Acute manifestations are headache, vomiting and dizziness with Signs of raised ICT -- this syndrome is known as pseudotumour cerebri. There is no residual damage after stopping the vitamin. Chronic toxicity is characterized by anorexia, dry itchy skin, weight loss, painful extremities, sparse hair, hepatosplenomegaly, hypoplastic anemia, benign intracranial hypertension. Carotinoids do not cause toxicity except reversible yellow color of the skin.HypervitaminosisCharacterized byHypervitaminosis A(Acute vitamin A intoxication was first described by Arctic explorers who develop headache, diarrhea and dizziness after eating polar bear liver. The liver of this animal is particularly rich in vit.A).# Anorexia,# Headache,# Hepatosplenomegaly,# Irritability,# Scaly dermatitis,# Patchy loss of hair,# Bone pain, and# Hyperostosis.Hypervitaminosis D# Hypotonia# Anorexia, Weight loss# Iritability# Polydipsia# Constipation# Pallor# Failure to thrive# Calciuria due to hypercalcemia# Proteinuria due to damage to renal tubules# Metastatic Calcification of many soft tissues, and eventual renal failure.# Sodium versenate may be used to chelate Ca from the body.Hypervitaminosis K[has not been described well)# Gastrointestinal disturbances and anemia.Hypervitaminosis E(doses > 800 mg/day)# Reduces platelet aggregation and interferes with vitamin K metabolism.# Nausea, Flatulence, Diarrhea at > 1 g/day.Ingestion of megadoses of pyridoxine (vitamin B6)# Can produce peripheral neuropathy.- Vitamin A intoxication is a rare cause of hypercalcemia and is most commonly a side effect of dietary faddism.- Calcium levels can be elevated into the 3 to 3.5 mmol/L (12 to 14 mg/dL) range after the ingestion of 50,000 to 100,000 units of vitamin A daily (10 to 20 times the minimum daily requirement).- Typical features of severe hypercalcemia include fatigue, anorexia, and, in some, severe muscle and bone pain.- Excess vitamin A intake is presumed to increase bone resorption.- The diagnosis can be established by history and by measurement of vitamin A levels in serum.- Occasionally, skeletal X-rays reveal periosteal calcifications, particularly in the hands.- Hypervitaminosis A - key imaging features:# Children: Metatarsal and ulnar hyperostosis- Cupping and splaying of metaphyses- Widening of cranial sutures# Adults: Vertebral osteophytosis (particularly cervical spine)- Appendicular enthesopathic changes (mild).
Cytosol
Mitochondria
Lysosome
Cell membrane
Nutrition