What causes hyperoxaluria? Approximately 14% of urinary oxalate comes from dietary absorption and the remainder from metabolism of glyoxylate and ascorbic acid. Increased oxidation of glyoxylate to oxalate occurs in the rare autosomal recessive hereditary hyperoxaluria. The clinically more important enteric hyperoxaluria occurs with small bowel resection, bypass, or inflammation. Small bowel disease may cause …
How do changes in calcium intake help distinguish the different types of absorptive hypercalciuria and renal leak hypercalciuria? In AH-II, the 24-hour urine calcium normalizes with a restricted calcium diet (400 mg/day) because the absorptive excess is not as severe. However, the 24-hour urine calcium during calcium restriction remains high in AH-I because of marked …
How would you distinguish among the various forms of Idiopathic Hypercalciuria Forms of Idiopathic Hypercalciuria LABORATORY VALUE AH-I AH-II AH-III RH Serum calcium Normal Normal Normal Normal Serum phosphorus Normal Normal ↓ Normal Serum intact PTH Normal Normal Normal ↑ 24-hour urinary calcium (1-g calcium diet) ↑ ↑ ↑ ↑ Urine Ca/Cr ratio (1-g calcium …
What is the etiology and pathophysiology of Idiopathic Hypercalciuria? IH affects 10% of the general population and 40% of stone formers. The four types of IH are AH-I, AH-II, AH-III, and RH. AH-I and AH-II result from increased intestinal sensitivity to calcitriol with intestinal calcium hyperabsorption and higher numbers of vitamin D receptors in osteoblasts, …
How do the serum calcium level and dietary sodium intake affect hypercalciuria? To help prevent hypercalcemia, nonrenal elevation in serum calcium causes an increase in both filtered calcium and urinary calcium. Increased sodium delivery to Henle’s loop and the distal tubule also raises urinary calcium. In non–stone formers, urinary calcium excretion increases about 40 mg …
How do the serum calcium level and dietary sodium intake affect hypercalciuria Read More »
How to calculate the normal filtered and excreted load of urinary calcium? The serum calcium concentration is normally about 10 mg/dL. The kidney filters complexed and free calcium, which make up 60% of the total, or 6 mg/dL. The normal glomerular filtration rate (GFR) is 120 mL/min. Thus, the filtered load of calcium is 6 …
How to calculate the normal filtered and excreted load of urinary calcium Read More »
How does the kidney handle calcium? Approximately 60% of the serum calcium is ionized or complexed and freely filtered by the glomerulus. The kidney reabsorbs 98% of the filtered calcium passively throughout the nephron. Sixty percent of the reabsorption occurs in the proximal convoluted tubule, 30% in Henle’s loop, and 10% in the distal tubule. …