Classically, we are notified to see a patient with hypercalcemia and one of the diagnosis that is made is primary hyperparathyroidism (PHPT). Due to the elevated PTH, what other electrolytes can go out of order?
1. Hypophosphatemia: Elevated PTH levels tend to lead to phosphate wasting in the urine. Proximal tubular absorption of phosphorus( Na –Phos co transporter) is blocked leading to renal wasting.
2. Hypomagnesemia: This one is interesting as hypercalcemia would lead to decrease magnesium absorption via Ca-Sensing receptor in the TAL but PTH would increase magnesium absorption. But net effect usually is “ hypercalcemia” wins leading to mg wasting as well. This in turn might lead to hypokalemia as well.
3. Metabolic acidosis: Elevated PTH levels lead to decrease proximal bicarbonate absorption and leading to mild metabolic acidosis. This is usually seen when you have AKI as well compounding this problem.