Parathyroid Diseases (PTH)

Order the pth test to evaluate the level of parathyroid hormone in the blood to help diagnose the cause of low or high calcium. Learn about your health today with Ulta Lab Tests!


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Serum calcium is involved in the regulation of neuromuscular and enzyme activity, bone metabolism and blood coagulation. Calcium blood levels are controlled by a complex interaction of parathyroid hormone, vitamin D, calcitonin and adrenal cortical steroids. Calcium measurements are useful in the diagnosis of parathyroid disease, some bone disorders and chronic renal disease. A low level of calcium may result in tetany.

Urinary calcium reflects dietary intake, rate of calcium absorption by the intestine and bone resorption. Urinary calcium is used primarily to evaluate parathyroid function and the effects of vitamin D. A significant number of patients with primary hyperparathyroidism will have elevated urinary calcium. However, there are other clinical entities that may be associated with increased urine calcium: Sarcoidosis, Paget's disease of bone, vitamin D intoxication, hyperthyroidism and glucocorticoid excess. Decreased urine calcium is seen with thiazide diuretics, vitamin D deficiency and familial hypocalciuric hypercalcemia.


Urinary calcium reflects dietary intake, rate of calcium absorption by the intestine and bone resorption. Urinary calcium is used primarily to evaluate parathyroid function and the effects of vitamin D. A significant number of patients with primary hyperparathyroidism will have elevated urinary calcium. However, there are other clinical entities that may be associated with increased urine calcium: Sarcoidosis, Paget's disease of bone, vitamin D intoxication, hyperthyroidism and glucocorticoid excess. Decreased urine calcium is seen with thiazide diuretics, vitamin D deficiency and familial hypocalciuric hypercalcemia.

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The ionized calcium is determined by an ion selective electrode methodology. The result that is generated is pH adjusted. The result is empirically based on a measured pH and ionized calcium concentration normalized to a pH of 7.40. This calculation compensates for in vitro changes in pH due to loss of CO2 through specimen handling. Ionized calcium represents the true "bioavailable" calcium in the circulation. In situations where the total calcium is normal but does not fit the clinical picture, e.g., hyperparathyroidism, a determination of the ionized calcium will, many times, show an elevation in the "bioavailable" calcium component. This may be due to alterations in protein concentrations, especially albumin, that binds most of the calcium in the circulation.


This panel is designed for individuals diagnosed as having diabetes mellitus whose kidney disease has advanced to Stage 3/4 impairment. The panel affords the opportunity to assess electrolytes, phosphorus, serum creatinine/eGFR, hemoglobin, microalbumin, parathyroid hormone, calcium, and vitamin D. The grouping of these tests, readily identifiable as elements that adhere to guideline recommendations, is intended to facilitate the ready adherence to professional society clinical practice guidelines. Components of the testing related to the Management of CKD in diabetes, as outlined in the Standards of Medical Care in Diabetes 2013. These recommendations are in broad agreement with those published by the National Kidney Foundation and the American Association of Clinical Endocrinologists.

Clinical Significance

Phosphate, 24-Hour Urine with Creatinine - Phosphorus is present in many foods with a mean intake of approximately 1500 mg per day for adult males and about 1000 mg per day for adult females. Absorbed phosphate, under the influence of parathyroid hormone is readily excreted in the kidney. Measurement of urinary phosphorus generally reflects dietary intake hence, day-to-day excretion may show considerable variation.


The IntactParathyroid Hormone Assay is the recommendedinitial assay for the differential diagnosis ofcalcium-related abnormalities.

The assay is useful in making the diagnosis of primary hyperparathyroidism, secondary hyperparathyroidism, and a differential diagnosis of hypercalcemia. The assay helps in distinguishing hypercalcemia cause by either primary hyperparathyroidism or malignant disease.

The hormone Parathyroid Hormone (PTH) acts to increase serum calcium and 1-, 25- dihydroxyvitamin D concentrations, while decreasing phosphorus. Cross-reactivity with fragment 7-84 may occur in patients with renal insufficiency. The BioIntact PTH assay is considered the most reliable. Parathyroid function is related to the calcium concentration so both results should be interpreted together.


Surgical treatment of hyperparathyroidism relies on the ability to accurately identify parathyroid tissue. The use of fine-needle aspirate (FNA) with measurement of intact parathyroid hormone (PTH) levels in suspected parathyroid cysts or adenomas is used to identify parathyroid tissue and has been proven to be a useful surgical adjunct in the treatment of hyperparathyroidism.



The average person has four parathyroid glands. These glands are button-sized and are situated at the base of the throat near the thyroid gland. Parathyroid glands produce a hormone called parathyroid (PTH) that is responsible for regulating the quantity of calcium in the blood.

Calcium is a mineral that is essential in the formation of bones, teeth, clotting of blood, and proper functioning of the heart, nerves, and muscles. About 99% of the calcium in the human body is found in the bones and teeth, while the rest circulates in the blood. Some calcium is eliminated from the body every day through urine.

To regulate the amount of calcium in the blood, the parathyroid hormone acts as part of a feedback system that includes vitamin D, phosphorus (as phosphate), and calcium. Phosphorus is another mineral that collaborates with calcium in its numerous operations in the body. Most of it combines with calcium to assist in the formation of teeth and bones. Vitamin D boosts the absorption of phosphate and calcium in the digestive system.

The parathyroid glands’ role is to ensure that the amount of calcium in the blood remains within a specific range. As the amount of calcium in the blood reduces, the parathyroid glands produce and release PTH, which works to increase the amount of calcium in the blood in 3 ways:

PTH triggers the kidneys to reduce the removal of calcium through urine and increase the removal of phosphate through urine.

It acts on the kidneys to transform vitamin D from the inactive to the active state. This, in turn, increases the quantity of calcium absorbed from food in the digestive system.

It boosts the release of calcium from bones into the bloodstream.

As the amount of calcium in the blood gets higher, the production of PTH by the parathyroid glands reduces. This feedback system ensures a dynamic but relatively stable concentration of calcium in the blood.

Parathyroid illnesses are conditions that affect the quantity of PTH (parathyroid hormone) produced, which in turn affects the amount of calcium in the bloodstream.

Hyperparathyroidism

Hyperparathyroidism is a condition characterized by the production of excess PTH by the parathyroid glands. It is divided into three groups: primary, secondary, and tertiary.

Primary hyperparathyroidism is a disease where the parathyroid glands are dysfunctional—the disease results in excess PTH in the blood as well as excess calcium in the blood. Since calcium is derived from the bones, they, in turn, become weak over time, increasing the risk of fractures.

About 85% of primary hyperparathyroidism cases are caused by a benign tumor (adenoma) in a single parathyroid gland. Less common causes are as a result of multiple adenomas or hyperplasia (an increase in the activity and size of 2 or more parathyroid glands). Very rare cases of the disease (less than 1%) are caused by parathyroid cancer, where tumors cause the production of excess PTH.

About 100,000 individuals in the U.S suffer from primary hyperparathyroidism each year. The disease is more common in individuals aged over 50 years and is more prevalent in women than men. In rare scenarios, the condition is caused by a genetic, endocrine syndrome (Men 1 or Men 2).

Secondary hyperparathyroidism is caused by low concentrations of calcium in the blood, which can happen due to the following:

  • Kidney failure: this can cause low amounts of active Vitamin D and elevated levels of phosphate, which lead to increased production of PTH.
  • Vitamin D deficiency.
  • Low calcium absorption caused by gastrointestinal disorders.
  • Tertiary hyperparathyroidism is rare and occurs when the main cause behind secondary hyperparathyroidism is fixed, but the parathyroid glands continue to over-produce PTH.

Hypoparathyroidism

Hypoparathyroidism is a PTH deficiency, and it can be a temporary or permanent condition. Hypoparathyroidism is not as common as hyperparathyroidism. Regardless of the cause, individuals with hypoparathyroidism have an elevated blood phosphorus level and a lower blood calcium level that may be mild or severe.

The leading cause of this condition is the removal of the parathyroid glands during surgical procedures necessary for the treatment of other conditions. Parathyroid glands may need to be removed if you have cancer of the throat or thyroid cancer. Surgery may also be necessary when treating hyperparathyroidism caused by hyperplasia (increase in the activity and size of the parathyroid glands). About 3 or 3.5 glands are removed, and the remaining glands or part of a gland can be auto transplanted to an individual’s forearm. If the remaining gland does not work as expected, hypoparathyroidism may occur.

In some cases, it is caused by damage to all parathyroid glands by an autoimmune condition.

In rare cases, it is caused by a failure of the glands to develop correctly.

Temporary hypoparathyroidism may occur soon after undergoing treatment for hyperparathyroidism. This is known as hungry bone syndrome and happens when PTH decreases rapidly, and the bones are forced to seek calcium from the bloodstream. It can also be observed in newly born infants whose mothers have hyperparathyroidism.

Radiotherapy for cancer patients that affects the neck or face: Too much exposure to radiation can damage the parathyroid glands.

Low levels of magnesium in the blood: normal levels of magnesium are necessary for PTH production and release.

Signs and Symptoms

Signs and symptoms of parathyroid disease are closely related with those of an individual with a low blood calcium concentration (hypocalcemia) that occurs with hypoparathyroidism or high blood calcium concentration (hypercalcemia) that occurs with hyperparathyroidism.

Some examples include:

  • Low calcium (hypothyroidism)
  • Depression or anxiety
  • Dry skin, brittle nails
  • Hair loss
  • Painful menstrual periods
  • Fatigue
  • Numbness and tingling sensations in the lips, toes, and fingers
  • Muscle cramps or twitching
  • Abdominal pain
  • High calcium (hyperparathyroidism):
  • Depression
  • Constipation
  • Kidney stones (excess calcium in the urine can crystalize and form stones)
  • Bone pain and fragile bones
  • Frequent urination
  • Feeling very thirsty
  • Abdominal pain, loss of appetite, nausea,
  • Fatigue

Many people with parathyroid disease are diagnosed at an early stage with minimal or no complications, but others may experience mild to severe complications before seeking medical care.

Tests

Testing is done to monitor, diagnose, and detect parathyroid diseases. The first sign of parathyroid disease may be an irregular blood calcium result on a routine blood test (like a CMP- Comprehensive Metabolic Panel). Some of the tests used to diagnose the parathyroid glands are noted below.

Some of the test results for patients with hyperparathyroidism include:

Calcium – elevated calcium levels, although many conditions may cause increased levels of calcium in the blood, so the test must be repeated multiple times to ascertain the cause.

PTH (parathyroid hormone)- usually elevated.

Urine calcium (one-day urine) – may be elevated due to hyperparathyroidism.

Some of the test results for patients with hypoparathyroidism include:

  • Low magnesium
  • High phosphate
  • Low PTH
  • Low calcium

Vitamin D – this test may be undertaken to establish whether an individual has a vitamin D deficiency that may be affecting calcium concentration in the blood.