The shape of the cysteine crystal is: (DBC Dec 2011)
a. Cystinuria is an autosomal recessive disorder characterized by a defect in intestinal and renal tubular transport of dibasic amino acids, resulting in excessive urinary excretion of cystine.
b. Although the defect results in high urinary concentrations of lysine, ornithine, and arginine as well, the poor solubility of cystine leads to stone formation.
c. Under normal conditions amino acids are freely filtered by the glomerulus and almost completely reabsorbed in the proximal tubules.
d. In cystinuria, the defect in transport of cystine results in high urinary levels.
e. There are several factors that determine the solubility of cystine, including cystine concentration, pH, ionic strength, and urinary macromolecules.
f. The main contributor to cystine crystallization is supersaturation because there is no specific inhibitor of cystine crystallization in the urine.