PTH Test in Dubai

The four parathyroid glands are small endocrine organs embedded in or near the posterior thyroid gland, each roughly the size of a grain of rice. Despite their anatomical proximity to the thyroid, they are functionally entirely separate, serving as the primary regulators of calcium and phosphate homeostasis. PTH is released within seconds in response to falling ionised calcium, acting on three target organs: bones (releasing calcium through osteoclast activation), kidneys (increasing calcium reabsorption and reducing phosphate retention, also activating vitamin D), and intestine (indirectly increasing calcium absorption via activated vitamin D). Together these actions rapidly restore serum calcium to normal, after which PTH secretion is suppressed by the rising calcium through a tight negative feedback loop.

Elevated PTH (hyperparathyroidism) is categorised by its cause. Primary hyperparathyroidism occurs when a parathyroid gland becomes autonomous, typically due to a benign adenoma, secreting excess PTH independent of calcium levels. The result is concurrent elevated calcium and elevated PTH. Secondary hyperparathyroidism is an appropriate compensatory response to hypocalcaemia or vitamin D deficiency, with high PTH but low or normal calcium. Tertiary hyperparathyroidism develops in long-standing secondary hyperparathyroidism, particularly in kidney disease, when the glands become autonomously hyperactive despite calcium correction. Each type has different treatment implications.

Low or undetectable PTH (hypoparathyroidism) results in hypocalcaemia because there is insufficient PTH to maintain calcium levels. The most common cause is surgical removal or inadvertent damage to the parathyroid glands during thyroid or neck surgery. Autoimmune destruction, genetic conditions such as DiGeorge syndrome, severe magnesium deficiency (magnesium is required for PTH secretion), and radiation damage are other causes. Low PTH with high calcium suggests the hypercalcaemia is from a non-PTH source, such as malignancy, vitamin D toxicity, or granulomatous disease.

The only curative treatment for primary hyperparathyroidism is surgical parathyroidectomy, removing the causative adenoma or hyperplastic gland. Minimally invasive parathyroidectomy guided by preoperative imaging with technetium-99m sestamibi scan and neck ultrasound achieves cure rates above 95 percent. Surgery is recommended when calcium is significantly elevated, when kidney stones, osteoporosis, or renal impairment are present, or in patients under 50. For those who decline or are unsuitable for surgery, cinacalcet (a calcimimetic drug that reduces PTH secretion) and bisphosphonates to protect bone can manage the condition, with regular monitoring of calcium, PTH, and bone density.

Vitamin D deficiency causes reduced intestinal calcium absorption, lowering blood calcium and triggering compensatory PTH elevation (secondary hyperparathyroidism). This is extremely common in the UAE and Middle East, where sun avoidance due to heat, skin coverage, and indoor lifestyles produce endemic vitamin D deficiency. Chronically elevated PTH due to vitamin D deficiency draws calcium from bones to compensate, contributing to osteoporosis and bone pain. Vitamin D supplementation corrects the deficiency, allowing calcium absorption to improve and PTH to normalise. This is why PTH and 25-OH vitamin D should always be measured together for accurate interpretation.

PTH values are only interpretable in the context of simultaneous calcium. A PTH of 80 pg/mL is normal if calcium is normal but indicates primary hyperparathyroidism if calcium is elevated — because in that situation PTH should be suppressed by the high calcium. Conversely, a PTH of 80 pg/mL with low calcium is an appropriate secondary response. The PTH-calcium relationship (whether they move in the same or opposite direction) is the key diagnostic discriminator. Our laboratory routinely reports PTH alongside calcium and phosphate in the same panel to ensure clinically useful interpretation.

Yes. Primary hyperparathyroidism increases urinary calcium excretion (hypercalciuria) through multiple mechanisms including increased bone calcium release and increased intestinal absorption via activated vitamin D. This elevated urinary calcium promotes calcium oxalate and calcium phosphate kidney stone formation. Approximately 15 to 20 percent of primary hyperparathyroidism patients have or develop kidney stones; conversely, primary hyperparathyroidism should be excluded in any patient presenting with recurrent calcium kidney stones through calcium and PTH measurement. Parathyroidectomy significantly reduces stone recurrence risk.

Chronically elevated PTH, as in primary hyperparathyroidism, stimulates osteoclast-mediated bone resorption to release calcium from the skeleton. This disproportionately affects cortical bone such as the distal radius and hip, while trabecular bone such as the lumbar spine is relatively spared in primary disease. Bone mineral density measured by DXA scan typically shows reduced density at the hip and forearm in primary hyperparathyroidism. After successful parathyroidectomy, bone density improves significantly over the following 1 to 3 years. Interestingly, intermittent low-dose PTH (teriparatide) is used therapeutically as an anabolic bone treatment for osteoporosis, demonstrating the complex site- and dose-dependent effects of PTH on bone.