Table 1 ∣.

Common dietary risk factors for calcium and uric acid stones

Dietary risk factor	Mechanism	Urinary aberrationa	Specific stone risk
Fluid intake insufficient to maintain suitably low urine supersaturation	Concentrated urine	Increased urine supersaturation for crystal formation	All types of stones
Intake of bicarbonate precursors insufficient to compensate for acidogenic foods in diet	High dietary acid load inducing bone resorption and increased renal citrate reabsorption	Hypercalciuria Hypocitraturia Overly acidic urine	CaOx, CaPhos, uric acid
Excessive intake of salt (as NaCl)	Expansion of extracellular volume and decreased renal calcium reabsorption in nephron	Hypercalciuria	CaOx, CaPhos
Excessive calcium supplementation (above the DRI)b	Increased intestinal calcium absorption	Hypercalciuria	CaOx, CaPhos
Excessive vitamin D supplementation (above the DRI)c	Increased intestinal calcium absorption	Hypercalciuria	CaOx, CaPhos
Vitamin D intake insufficient to maintain normal limits	Secondary hyperparathyroidism and bone resorption	Hypercalciuria	CaOx, CaPhos
Calcium intake insufficient to meet needs for bone, especially in the context of increased dietary protein intake	Rise in calcitriol production	Hypercalciuria	CaOx, CaPhos
Calcium intake insufficient to compensate for oxalate load in the diet, especially in the context of malabsorption	Increased intestinal absorption of dietary oxalate	Hyperoxaluria	CaOx
Excessive vitamin C supplementation (>2,000 mg/day)	Increased biosynthesis of oxalate
Excessive intake of animal-derived purines	Increased uric acid biosynthesis	Hyperuricosuria	Uric acid

CaOx, calcium oxalate; CaPhos, calcium phosphate; DRI, dietary reference intake. ^aAssessed using 24-h urine collection. ^bDRI for calcium is 1,200 mg/day for adults >19 years of age. ^cDRI for vitamin D is 600 International Units (15 mcg)/day for adults.