Parathyroid Hormone (PTH)
CPT Code(s):
83970
Turnaround Time:
4 hours
Specimen Requirements
Preferred Specimen:
Serum and Whole Blood
Minimum Volume:
1.0 mL
Transport Container:
Serum Separator Tube (SST) or Red Top Tube and Lavender Top Tube
Transport Temperature:
Room Temperature
Collection Instructions:
Allow blood to clot completely prior to centrifugation. Separate serum from cells within 45 minutes of collection.
Rejection Criteria:
Sodium Citrate plasma; gross hemolysis; lipemia; improper labeling
Stability Criteria
Room Temperature:
8 hours (Serum), 24 hours (Plasma)
Refrigerated:
8 hours (Serum), 14 days (Plasma)
Frozen:
Unacceptable
Clinical Significance
The Parathyroid Hormone (PTH) test is clinically significant and diagnostically useful for assessing parathyroid gland function and calcium metabolism in the body. It measures the level of PTH in the blood, which is produced by the parathyroid glands and plays a crucial role in maintaining calcium balance. The specific clinical significance and diagnostic use of PTH include:
1. Evaluating Parathyroid Gland Function: PTH is primarily used to assess the function of the parathyroid glands. High levels of PTH may indicate hyperparathyroidism, a condition in which the parathyroid glands produce excessive amounts of PTH. This can lead to increased calcium levels in the blood, causing symptoms such as bone pain, kidney stones, and weakened bones. Conversely, low levels of PTH may suggest hypoparathyroidism, where the parathyroid glands produce insufficient PTH. This can result in low blood calcium levels and symptoms such as muscle cramps, tingling, and abnormal heart rhythms.
2. Diagnosing Calcium Disorders: PTH is used to diagnose and monitor various calcium disorders. Elevated PTH levels, along with high blood calcium levels, can indicate primary hyperparathyroidism, a condition characterized by excessive calcium release from bones and decreased calcium excretion by the kidneys. On the other hand, low PTH levels, along with low blood calcium levels, may suggest secondary hypoparathyroidism, which can be caused by chronic kidney disease or vitamin D deficiency.
3. Monitoring Chronic Kidney Disease: PTH is particularly important in monitoring patients with chronic kidney disease (CKD). As kidney function declines, the ability to convert inactive vitamin D into its active form decreases, leading to reduced calcium absorption from the intestines and increased PTH production. Elevated PTH levels in CKD patients indicate secondary hyperparathyroidism, which contributes to bone loss and mineral imbalance. Regular monitoring of PTH levels helps guide treatment decisions and interventions to manage bone and mineral disorders in patients with CKD.
4. Assessing Bone Health: PTH is involved in regulating bone turnover and maintaining bone density. PTH is used in the evaluation of osteoporosis, a condition characterized by decreased bone density and increased fracture risk. PTH levels can help assess the severity of osteoporosis and guide treatment strategies, such as the use of medications that affect bone metabolism.
5. Monitoring Treatment Efficacy: PTH is used to monitor the effectiveness of treatment for parathyroid disorders or calcium abnormalities. Serial measurements of PTH levels can help assess the response to interventions, such as surgery to remove parathyroid adenomas or pharmacological therapies aimed at regulating PTH secretion.
In summary, PTH is a valuable diagnostic tool for evaluating parathyroid gland function, diagnosing calcium disorders, monitoring chronic kidney disease, assessing bone health, and monitoring treatment efficacy. It provides important information about calcium metabolism and helps guide appropriate management strategies for patients with parathyroid disorders and related conditions.