PTH and parathyroid gland adenoma: Typically, PTHrP is associated with hypercalcemia and low or suppressed PTH levels. In some cases of parathyroid adenoma, post-translational changes may lead to the production of specific PTH levels that standard serum PTH assays may not detect. Some studies have suggested increasing serum dilution during PTH sample analysis and adjusting for dilution factors in cases where parathyroid adenoma is present, but regular assays yield low serum PTH levels.