Patient Scenario: Low PTH, hyperphosphatemia & low/normal calcium
Assessing the Clinical and Laboratory Parameters
Prior Parathyroidectomy? Low or undetectable PTH levels are an expected finding.
Parathyroids intact (or partially resected/reimplanted during prior PT surgery)? PTH secretion may be suppressed secondary to over-use of calcium based binders and/or use of vitamin D analogues; Parathyroid gland remains sensitive to ambient ionized calcium, i.e. is not autonomous
Approximately 12% of all patients are in this category.
Lowering dialysis calcium from 1.25 to 1.0 mmol/L may allow increased doses of calcium based binders for phosphate control, and the resultant transient post-dialysis hypocalcemia may allow restoration of PTH secretion. Very prolonged dialysis times (e.g. daily or nocturnal dialysis) usually achieve better phosphate control, but increased intermittent times up to 5 hours may have little effect