Normal parathyroid hormone, or PTH, levels are 10 to 55 picograms per milliliter, according to Healthline. PTH levels over 55 picograms per milliliter may indicate chronic kidney disease, vitamin D disorders, parathyroid gland tumors or a lack of calcium in the diet.
PTH levels under 10 picograms per millimeter may indicate an autoimmune disorder, sarcoidosis, vitamin D intoxication, low blood magnesium or hypoparathyroidism, states Healthline. Low PTH levels can also indicate cancer that has spread to the bones.
Doctors evaluate PTH test results in conjunction with calcium test results to ensure proper balance, explains Healthline. Balanced PTH and calcium levels signal that the parathyroid is functioning correctly.