PTH

• Alternative Names

  Parathormone; Parathormone (PTH) intact molecule; Parathyroid hormone

• How the test is performed

  Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

  Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

  Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

  In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

• How to prepare for the test

  You should not eat or drink anything except water for 10 to 12 hours before the test.

• How the test will feel

  When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

• Why the test is performed

  Your doctor may order this test if you have abnormal calcium or phosphorus levels and a PTH abnormality is suspected.

• Normal Values

  Normal values are 10-55 picograms per milliliter (pg/mL). Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

• What abnormal results mean

  Greater-than-normal levels may occur with:

  • Chronic kidney failure
  • Familial hypocalciuric hypercalcemia (FHH)
  • High phosphate levels (hyperphosphatemia)
  • Hyperparathyroidism
  • Increased blood lipids
  • Malabsorption syndrome
  • Osteomalacia in adults
  • Pregnancy or breastfeeding
  • Pseudohypoparathyroidism
  • Rickets in children
  • Use of certain medications such as rifampin, anticonvulsants, diuretics, lithium, and those containing phosphate
  • Vitamin D deficiency

  Lower-than-normal levels may occur with:

  • Accidental removal of parathyroid glands during neck surgery
  • Autoimmune destruction of parathyroid gland
  • Hypomagnesemia
  • Hypoparathyroidism
  • Metastatic bone tumor
  • Milk-alkali syndrome (taking too much calcium)
  • Radiation to the parathyroid glands
  • Sarcoidosis
  • Vitamin D intoxication

  Other conditions under which the test may be performed:

  • Multiple endocrine neoplasia (MEN) II
  • Multiple endocrine neoplasia (MEN) I
  • Secondary hyperparathyroidism
• What the risks are
  • Excessive bleeding
  • Fainting or feeling light-headed
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)
• References

  Wysolmerski JJ, Insogna KL. The parathyroid glands, hypercalcemia, and hypocalcemia. In: Kronenberg HM, Schlomo M, Polansky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. St. Louis, MO: WB Saunders;2008:chap 266.

Review Date: 10/14/2009

Reviewed By: Ari S. Eckman, MD, Division of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.