Secondary hyperparathyroidism
| Secondary hyperparathyroidism | |
|---|---|
 |
|
| Thyroid and parathyroid. | |
| Classification and external resources | |
| Specialty | Endocrinology |
| ICD-10 | E21.1 |
| ICD-9-CM | 252.02, 588.81 |
| DiseasesDB | 6301 |
| MedlinePlus | 000318 |
| MeSH | D006962 |
Secondary hyperparathyroidism (SHPT) refers to the excessive secretion of parathyroid hormone (PTH) by the parathyroid glands in response to hypocalcemia (low blood calcium levels) and associated hyperplasia of the glands. This disorder is especially seen in patients with chronic kidney failure. It is often—although not consistently—abbreviated as SHPT in medical literature.
Bone and joint pain are common, as are limb deformities. The elevated PTH has also pleiotropic effects on the blood, immune system, and neurological system.
The PTH is elevated due to decreased levels of calcium or 1,25-dihydroxy-vitamin D3. It is usually seen in cases of chronic kidney disease or defective calcium receptors on the surface of parathyroid glands.
Chronic kidney failure is the most common cause of secondary hyperparathyroidism. Failing kidneys do not convert enough vitamin D to its active form, and they do not adequately excrete phosphate. When this happens, insoluble calcium phosphate forms in the body and removes calcium from the circulation. Both processes lead to hypocalcemia and hence secondary hyperparathyroidism. Secondary hyperparathyroidism can also result from malabsorption (chronic pancreatitis, small bowel disease, malabsorption-dependent bariatric surgery) in that the fat-soluble vitamin D can not get reabsorbed. This leads to hypocalcemia and a subsequent increase in parathyroid hormone secretion in an attempt to increase the serum calcium levels.
If the underlying cause of the hypocalcemia can be addressed, the hyperparathyroidism will resolve. In people with chronic renal failure, treatment consists of dietary restriction of phosphorus, supplements with an active form of vitamin D such as calcitriol, doxercalciferol, paricalcitol, etc. and phosphate binders which can be divided into calcium-based and non-calcium based.
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