Final answer:
Decreased reabsorption of cystine from the urine in young individuals can lead to recurrent kidney stone formation, characterized by pathognomonic hexagonal crystals. These cystine stones are often associated with cystinuria, and they are part of a broader category of kidney stones primarily composed of calcium salts. Kidney stones can result from various metabolic conditions and can cause severe pain and hematuria.
Step-by-step explanation:
Kidney Stones and Recurrent Formation
Recurrent kidney stone formation at a young age due to decreased reabsorption of cystine from the urine is associated with pathognomonic hexagonal crystals. These hexagonal crystals are indicative of cystine stones, which occur in individuals with a condition known as cystinuria. In cystinuria, the kidneys fail to reabsorb cystine adequately, leading to its accumulation and subsequent stone formation. Kidney stones can cause symptoms such as severe colicky pain and hematuria, which is the presence of blood in the urine. The majority of kidney stones are composed of calcium salts like Ca(O₂CCO₂) H₂O (calcium oxalate) and Ca3(PO4)2 (calcium phosphate), but cystine stones are distinct in their composition and cause.
Cystine stones are just one type of kidney stone, a problem that can also arise from conditions like hyperparathyroidism and renal tubular acidosis. Factors such as high levels of calcium, oxalate, and phosphorus in the urine contribute to the formation of kidney stones, and certain dietary and metabolic conditions can exacerbate this risk.