Calcium in urine stone is present in all of the following except:
a. UTI
b. Secondary hyperparathyroidism.
(b) In 2ry hyperparathyroidism, hypocalcemia due to e.g. chronic renal failure is the cause of increased parathormone. Stones due to hyperparathyroidism only occur with the 1ry or 3ry disease.
Calcium is precipitated in stones with oxalate (at acid or neutral pH), or less commonly with urate (at acidic pH) or with phosphate (at normal urine pH). Causes of hypercalciurea include:
- ↑intestinal calcium absorption (↑P level→↑vit D→↑Ca absorption Or in case of hypervitaminosis D.
- Lack of renal tubular reabsorption e.g. with furosamide.
- Loss of Ca from bone (due to mobilization as in 1ry & 3ry hyperparathyroidism, due to bone destruction or due to Cushing's and thyrotoxicosis)
Otherwise, UTI causes stones at alkaline pH where ammonium is high and mixed stones form due to obstructing Ca stone which favors infection and precipitation of ammonia salts.
a. UTI
b. Secondary hyperparathyroidism.
(b) In 2ry hyperparathyroidism, hypocalcemia due to e.g. chronic renal failure is the cause of increased parathormone. Stones due to hyperparathyroidism only occur with the 1ry or 3ry disease.
Calcium is precipitated in stones with oxalate (at acid or neutral pH), or less commonly with urate (at acidic pH) or with phosphate (at normal urine pH). Causes of hypercalciurea include:
- ↑intestinal calcium absorption (↑P level→↑vit D→↑Ca absorption Or in case of hypervitaminosis D.
- Lack of renal tubular reabsorption e.g. with furosamide.
- Loss of Ca from bone (due to mobilization as in 1ry & 3ry hyperparathyroidism, due to bone destruction or due to Cushing's and thyrotoxicosis)
Otherwise, UTI causes stones at alkaline pH where ammonium is high and mixed stones form due to obstructing Ca stone which favors infection and precipitation of ammonia salts.
