Hypercalciuria - what is, definition and causes
Excessive excretion of calcium in the URINE. About 80 percent of people who have kidney stones (NEPHROLITHIASIS) or BLADDER stones (UROLITHIASIS) have hypercalciuria. In most people the circumstance appears a combination of factors that typically include high dietary calcium intake, insufficient water consumption (resulting in low urine volume), and physical inactivity. The water and citrate content of the urine normally allows most of the calcium the KIDNEYS extract from the BLOOD to dissolve and pass from the body. When urine volume and citrate concentration are low, calcium in the urine combines with other minerals (usually oxalate or phosphate) to form crystalline structures. Over time these structures harden or calcify (called calculi). Inactivity contributes to calculus formation because it allows mineral sediments to settle, facilitating their crystallization.
Other Causes of Hypercalciuria
Other causes of hypercalciuria include endocrine disorders such as HYPERPARATHYROIDISM and ADDISON’S DISEASE, kidney dysfunction, and MALABSORPTION disorders of the gastrointestinal system. Many people who have hypercalciuria do not have nephrolithiasis or urolithiasis, though the presence of excess calcium in the urine raises their risk for developing either condition. Routine urinalysis often detects hypercalciuria. Doctors generally recommend increased water consumption, maintaining dietary calcium intake at recommended levels for BONE health, and daily physical activity. Many people also benefit from thiazide diuretic medications, which act to slow the extraction of calcium in the kidneys as well as to increase the volume of urine. Many stones that form as a consequence of hypercalciuria will pass through the urinary tract without medical intervention, though they require treatment when they cause significant pain or an obstruction in the kidney, URETER, bladder, or URETHRA.
See also CYSTINURIA; FANCONI’S SYNDROME; HYPEROXALURIA; RENAL TUBULAR ACIDOSIS.
