Parathyroid Hormone (PTH): Normal Ranges and Health Risks

What Is Parathyroid Hormone (PTH)?

Parathyroid hormone (PTH) is a key hormone the parathyroid glands produce. They are small glands located in the neck behind the thyroid. 

Its main role in the body is to regulate calcium levels in the blood, bones, and kidneys. 

PTH increases calcium absorption in the intestines, encourages the kidneys to retain calcium, and stimulates the release of calcium from bones into the bloodstream.

When levels of calcium in the blood are too low, the parathyroid glands release more PTH to restore normal calcium levels. Conversely, when calcium is too high, PTH levels decrease.

PTH testing is important for diagnosing conditions related to abnormal calcium levels, such as hyperparathyroidism, kidney disease, and bone disorders.

When Is Parathyroid Hormone Testing Recommended?

A parathyroid hormone test is typically prescribed when there is a suspicion of an imbalance in calcium levels or a condition affecting the parathyroid glands. The test helps determine whether the parathyroid glands are functioning properly and contributing to abnormal calcium levels.

Parathyroid hormone testing is recommended in cases of:

• Abnormal calcium levels: High or low calcium levels detected through blood tests.
• Bone pain or weakness: When unexplained bone pain or weakness occurs, PTH levels may be checked to assess bone health.
• Kidney stones: Frequent kidney stones can be a sign of abnormal calcium metabolism.
• Fatigue or muscle weakness: These symptoms can be linked to calcium or PTH imbalances.
• Frequent urination and excessive thirst: These may indicate kidney problems related to calcium imbalance.
• Numbness or tingling in the limbs: This can occur when calcium levels are too low.

How Is Parathyroid Hormone Testing Conducted?

Parathyroid hormone levels are typically measured through a blood test, where a sample of blood is taken from a vein, usually in the arm. 

In many cases, PTH is tested along with calcium levels, as these two are closely connected. 

This combined approach helps to identify whether abnormal calcium levels are caused by parathyroid gland dysfunction or another underlying condition.

Common panels that include PTH testing:

• Comprehensive Metabolic Panel (CMP)
• Parathyroid panel (specifically for PTH)

There are typically no special preparations for a PTH test. However, your healthcare provider may advise you to avoid eating or drinking for a few hours before the test, depending on any accompanying tests.

What Are the Normal Parathyroid Hormone Levels?

The normal ranges for parathyroid hormone levels can vary slightly depending on the age group, with different reference values for children, adults, and pregnant women.

• Children:
  • Up to 1 year old: 8.0-61 pg/mL
  • Up to 10 years old: 11-59 pg/mL
  • Up to 17 years old: 11.4-14.3 pg/mL
• Adults: 15-65 pg/mL
• Pregnant Women:
  • Up to 12 weeks: 10-15 pg/mL
  • Up to 27 weeks: 18-25 pg/mL
  • Up to 42 weeks: 9-26 pg/mL

Note: The units of measurement and the normal ranges can differ depending on the laboratory and the specific methods used

What Do Abnormal Levels Mean?

Parathyroid Hormone High Levels

Elevated PTH levels indicate that the body may be trying to increase calcium levels in the blood, possibly due to an underlying condition. High PTH levels are typically linked to issues involving calcium regulation, bones, or the kidneys.

Causes of high PTH levels include:

• Primary hyperparathyroidism: Overactive parathyroid glands produce too much PTH, leading to high calcium levels in the blood.
• Kidney disease: Reduced kidney function can cause calcium levels to drop, leading to increased PTH production.
• Vitamin D deficiency: Low vitamin D levels can cause the body to produce more PTH to maintain calcium levels.
• Bone disorders: Conditions like osteomalacia (softening of bones) may lead to elevated PTH as the body tries to compensate for weakened bones.
• Certain cancers: PTH-related protein may be secreted by tumors, especially in kidney or lung cancer.

• Work closely with your doctor to identify the underlying cause.
• Monitor your calcium and vitamin D levels regularly.
• Stay physically active to strengthen bones.
• Maintain a balanced diet with adequate calcium intake, but avoid excessive amounts without medical guidance.
• Follow a treatment plan recommended by your healthcare provider, which may include lifestyle changes or further testing.

Parathyroid Hormone Low Levels

Low PTH levels suggest that the parathyroid glands are underactive or that another condition is suppressing PTH production. This can result in higher-than-normal calcium levels in the blood, which might also lead to various health issues.

Causes of low PTH levels include:

• Primary hypoparathyroidism: The parathyroid glands do not produce enough PTH, often due to autoimmune diseases or surgical removal.
• Magnesium deficiency: Low magnesium levels can impair parathyroid gland function and reduce PTH production.
• Autoimmune disorders: Certain autoimmune diseases can attack the parathyroid glands, leading to low PTH levels.
• Hypercalcemia: When calcium levels are too high, PTH naturally decreases to bring calcium levels down.

• Get regular calcium level checks to monitor for changes.
• Include foods rich in calcium and magnesium in your diet.
• Work with your healthcare provider to explore treatment options for restoring PTH balance.
• Avoid overconsumption of vitamin D and calcium without medical advice, as this can further suppress PTH levels.

Which Specialist Should You Consult?

If you have abnormal parathyroid hormone levels or symptoms related to calcium imbalance, the specialist you should consult is an endocrinologist. Endocrinologists specialize in the glands and hormones of the body and can provide a more detailed diagnosis and treatment plan based on your PTH levels.