What is important in the history and physical examination of patients with kidney stones? Obtain present, past, and family histories of stone disease, and ask about use of guaifenesin, ephedrine, indinavir, triamterene, sulfonamides, acyclovir, and vitamins A, C, and D. Determine fluid intake and sources of excess calcium, salt, oxalate, uric acid, and protein. Physical …
What are the presenting symptoms and signs of renal stones? Approximately 30% of renal stones are asymptomatic and are found incidentally on radiographic studies. Seventy percent of renal stones are symptomatic. The patient may present with a dull ache in the posterior flank. However, the classic presenting symptom of renal stones is excruciating unilateral flank …
What is the role of diet in the formation of kidney stones? The high animal protein (beef, poultry, pork, and fish) intake of many Americans (> 1.5–2 g/kg/day) acidifies the urine with phosphoric, sulfuric, and uric acids; decreases urinary citrate; increases urinary calcium; and raises the risk for nephrolithiasis. Higher protein diets, such as the …
What conditions cause low levels of urinary citrate? Patients with hypocitraturia excrete < 320 mg/day while optimal levels are closer to 640 mg/day. Idiopathic hypocitraturia occurs in < 5% of patients with calcium stones, and secondary hypocitraturia may occur in 30%. Citrate is freely filtered by the glomerulus, 75% is reabsorbed by the proximal renal …
What conditions cause low levels of urinary citrate Read More »
How does urinary pH relate to renal stones? Because uric acid has a pKa of 5.5, acid urine shifts the equilibrium so that the concentration of uric acid is higher than the concentration of sodium urate. At urine pH 6.5, only 10% is in the form of uric acid, and approximately 90% in the form …
How does hyperuricosuria contribute to renal stones? Uric acid stones develop in approximately 25% of patients with symptomatic tophaceous gout. Excessive urinary uric acid (> 600 mg/day) supersaturates the urine, crystallizes, and forms uric acid stones. However, most uric acid stone formers do not have gout, hyperuricemia, or hyperuricosuria. But all have a urinary pH …
How does hyperuricosuria contribute to renal stones Read More »
Why is hyperoxaluria important in nephrolithiasis? Oxalate is a significant component of the most commonly formed stones (calcium oxalate) and contributes to urine supersaturation. Previously, it was believed to be a much stronger stimulus to calcium oxalate stone formation compared with calcium. Newer data suggest that calcium may be just as potent; however, a high …
Why is hyperoxaluria important in nephrolithiasis Read More »