Hyperparathyroidism is a condition where the parathyroid glands produce too much parathyroid hormone (PTH), leading to imbalances in calcium levels. This hormonal imbalance can cause a range of symptoms, including fatigue, bone pain, and kidney stones. To diagnose hyperparathyroidism accurately, a combination of blood tests, urine analysis, and imaging scans is often required.
Understanding Hyperparathyroidism
Hyperparathyroidism occurs when one or more parathyroid glands produce too much parathyroid hormone (PTH), disrupting calcium balance in the body. Diagnosis begins by recognising symptoms such as fatigue, bone pain or kidney stones, but many cases are discovered incidentally during routine blood tests showing elevated calcium levels.
Serum Calcium Test
The first diagnostic clue is often high blood calcium levels found in a standard blood test. Persistent hypercalcaemia suggests a parathyroid problem, prompting further testing. It is important to measure albumin alongside calcium, as this helps correct for protein binding and gives a more accurate free calcium level.
Parathyroid Hormone (PTH) Levels
PTH levels are measured to confirm whether the raised calcium is caused by overactive parathyroid glands. In primary hyperparathyroidism, both calcium and PTH levels are elevated. If calcium is high but PTH is low, another cause should be investigated. This test is central to confirming the diagnosis.
Vitamin D Testing
Vitamin D deficiency can mimic or mask symptoms of hyperparathyroidism. Testing 25-hydroxyvitamin D levels is essential, as low vitamin D may elevate PTH levels as a compensatory response. It also helps guide treatment and ensures calcium metabolism is properly assessed during diagnosis and ongoing management.
Serum Phosphate and Alkaline Phosphatase
Low phosphate and high alkaline phosphatase levels can support the diagnosis, indicating disrupted mineral balance and increased bone turnover. These markers are useful in evaluating bone involvement and can help distinguish between different types of hyperparathyroidism, particularly in chronic kidney disease or secondary causes.
24-Hour Urinary Calcium Excretion
This test helps differentiate between familial hypocalciuric hypercalcaemia and primary hyperparathyroidism. In the latter, urinary calcium is usually high, while familial conditions typically show low calcium in the urine. It plays a crucial role in preventing unnecessary surgery in patients with inherited forms of calcium imbalance.
Bone Density Scan (DEXA)
A DEXA scan evaluates bone mineral density, especially in the spine, hip and forearm. Hyperparathyroidism can lead to bone thinning or osteoporosis. The results help determine whether bone loss is present and whether surgery or other treatments are necessary to prevent fractures and preserve long-term skeletal health.
Kidney Imaging and Function Tests
Since kidney stones are a common complication, imaging studies like ultrasound or CT scans may be used to detect them. Blood creatinine and estimated glomerular filtration rate (eGFR) assess overall kidney function, which is important in understanding whether the condition is affecting renal health or contributing to secondary hyperparathyroidism.
Sestamibi Scan for Gland Localisation
A sestamibi scan uses a radioactive tracer to identify overactive parathyroid glands. It helps plan surgery by localising which gland is enlarged. While not always definitive, it is a useful imaging technique often combined with ultrasound or CT to increase accuracy in preoperative planning.
Genetic Testing for Inherited Forms
In younger patients or those with a family history, genetic testing may be used to check for inherited syndromes such as MEN1 or MEN2. These tests provide insight into potential familial risk and guide both treatment decisions and long-term monitoring for patients and their relatives.
Conclusion
Diagnosing hyperparathyroidism involves more than a single test. It is a multi-step process that combines blood work, urine analysis and imaging to provide a clear and accurate assessment. If you suspect a problem or have symptoms like fatigue, kidney stones or persistent muscle pain, seek medical advice promptly.
