Alternate Names: Parathormone; Parathormone (PTH) intact molecule; Parathyroid hormone
How Performed: Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How To Prepare: Fast for 6 hours before the tests.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:
How It Feels: 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.
Risks:
- excessive bleeding
- fainting or feeling lightheaded
- hematoma (blood accumulating under the skin)
- infection (a slight risk any time the skin is broken)
- multiple punctures to locate veins
Why Performed: This test may be performed when PTH abnormality is suspected as a cause of abnormal calcium or phosphorus levels.
PTH is a protein hormone secreted by the parathyroid gland which is the most important regulator of body calcium and phosphorus.
PTH:
- increases the calcium and phosphorus release from bone
- decreases the loss of calcium and increases the loss of phosphorus in the urine
- increases the activation of 25-hydroxy vitamin D to 1,25-dihydroxy vitamin D in the kidneys
Secretion of PTH is regulated by the level of calcium in the blood. Low serum calcium causes increased PTH to be secreted, whereas increased serum calcium inhibits PTH release.
Normal Values: 10-55 pg/ml
Note: pg/ml = picograms per milliliter
Abnormal Results: Greater-than-normal levels may be associated with:
Lower-than-normal levels may be associated with:Additional conditions under which the test may be performed:
Cost:
Special Considerations: Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
