PTH and hyperphosphatemia: ADH is associated with hypocalcemia, hyperphosphatemia, hypomagnesemia, and inappropriately low or normal PTH concentrations; some patients may also be hypercalciuric (1, 4) or develop a Bartter-like syndrome characterized by hypokalemic alkalosis, renal salt wasting, and hyperreninemic hyperaldosteronism (5, 6).