Parathyroid disorders

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Parathyroid disorders

Overview

Classification

Hyperparathyroidism
Familial hypocalciuric hypercalcemia
Hypoparathyroidism
Pseudohypoparathyroidism

Diagnosis

Differentiating Parathyroid Disorders

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Usama Talib, BSc, MD [2], Seyedmahdi Pahlavani, M.D. [3]

Synonyms and keywords:

Overview

The parathyroid glands are small endocrine glands in the neck, usually located behind the thyroid gland, which produce parathyroid hormone. These glands were first discovered in the Indian Rhinoceros by Richard Owen in 1852. The sole function of the parathyroid glands is to maintain the body's calcium level within a very narrow range, so that the nervous and muscular systems can function properly. When blood calcium levels drop below a certain point, calcium-sensing receptors in the parathyroid gland are activated to release hormone into the blood. Parathyroid hormone (PTH, also known as parathormone) is a small protein that takes part in the control of calcium and phosphate homeostasis, as well as bone physiology. Parathyroid hormone has effects antagonistic to those of calcitonin. It increases blood calcium levels by stimulating osteoclasts to break down bone and release calcium. It also increases gastrointestinal calcium absorption by activating vitamin D, and promotes calcium uptake by the kidneys. Hyperparathyroidism is overactivity of the parathyroid glands resulting in excess production of parathyroid hormone (PTH). Overactivity of one or more of the parathyroid glands causes high calcium levels (hypercalcemia) and low levels of phosphorus in the blood. Hyperfunction of the parathyroid glands could be due to adenoma, hyperplasia or, rarely, carcinoma of the parathyroid glands. Hyperparathyroidism may present with symptoms of hypercalcemia, such as painful bones, kidney stones, abdominal pain, psychic moans, and fatigue. An elevated concentration of serum calcium with elevated parathyroid hormone level is diagnostic of primary hyperparathyoidism. Surgical therapy is preferred over medical therapy in primary hyperparathyroidism. Hypoparathyroidism is a disorder characterized by hypocalcemia due to insufficient secretion of PTH. Most common cause for hypoparathyroidism is post-surgical including thyroidectomy, parathyroidectomy, and radical neck dissection. Second most common cause for hypoparathyroidism is autoimmune including polyglandular autoimmune syndrome type 1 and isolated autoimmune hypoparathyroidism. Hypoparathyroidism should be differentiated from other causes of hypocalcemia. Causes of hypocalcemia other than hypoparathyroidism include pseudohypoparathyroidism, hypomagnesemia, hypovitaminosis D, chronic kidney disease, and relative hypocalcemia due to hypoalbuminemia. The hallmark of acute hypocalcemia due to hypoparathyroidism is tetany. A positive history of neck surgery and symptoms of hypocalcemia is suggestive of hypoparathyroidism. The most common symptoms of hypoparathyroidism include tetany, paresthesia, carpopedal spasms, and circumoral numbness. Common symptoms of hypoparathyroidism include abdominal pain, biliary colic, fatigue, muscle cramps, myoclonic jerks, new onset seizure due to hypocalcemia or worsening of seizures, and painful menstruation. Diagnosis of hypoparathyroidism is made by measurement of serum calcium (total and ionized), serum albumin (for correction), phosphate, intact parathyroid hormone (PTH), and 25-hydroxy vitamin D levels. Normal or inappropriately low serum intact parathyroid hormone (PTH) concentration in patients with subnormal serum albumin corrected total or ionized calcium concentration diagnostic of hypoparathyroidism. Pharmacologic medical therapies for hypoparathyroidism include calcium and Vitamin D3 supplementation. Severe hypocalcemia, a potentially life-threatening condition, is treated as soon as possible with intravenous calcium (e.g. as calcium gluconate).

Classification




 
 
 
 
 
 
 
 
 
 
 
 
 
Parathyroid disorders
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hyperparathyroidism
 
 
 
Familial hypocalciuric hypercalcemia
 
 
 
Hypoparathyroidism
 
 
 
Parathyroid hormone resistance diseases
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Primary
 
Secondary
 
Tertiary
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Post-surgical
 
Autoimmune
 
Genetic defects associated
 
Functional
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Pseudohypoparathyroidism
 
 
 
Acrodysostosis
 
 
 
 
Blomstrand chondrodysplasia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Pseudohypoparathyroidism type 1
 
 
 
Pseudohypoparathyroidism type 2
 
Acrodysostosis type 1
 
 
Acrodysostosis type 2
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Type 1A
 
 
Type 1B
 
 
 
Type 1C
 
 
Pseudopseudohypoparathyroidism
 

Diagnosis

Disorder Laboratory findings
Parathyroid hormone Serum calcium Serum phosphate Other findings
Hyperparathyroidism Primary hyperparathyroidism /Normal
Secondary hyperparathyroidism /Normal --
Tertiary hyperparathyroidism --
Familial hypocalciuric hypercalcemia Normal/ Normal/ --
  • Urinary calcium/creatinine clearance ratio
Hypoparathyroidism
Pseudohypoparathyroidism Type 1A
Type 1B
Type 1C
Pseudopseudohypoparathyroidism Normal Normal Normal --
Type 2
Acrodysostosis Acrodysostosis type 1
  • Multiple hormone resistance
Acrodysostosis type 2
  • Multiple hormone resistance
Blomstrand chondrodysplasia

Differentiating Parathyroid Disorders

  • The main presenting features of parathyroid disorders are related to calcium secretion. Accordingly, differentiating parathyroid disorders from other diseases is mainly dependent to changes in calcium level. Following algorithms are designed to differentiate diseases according to hypercalcemia and hypocalcemia.

Hypercalcemia



 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hypercalcemia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Repeat (Check ionized calcium or calcium corrected for albumin)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hypercalcemia confirmed
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Measure intact parathyroid hormone (PTH)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
PTH
 
 
 
 
 
 
 
Mildly ↑ PTH
 
 
 
 
 
 
PTH
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Hyperparathyroidism
 
 
 
 
 
 
 
Urinary calcium creatinine ratio
 
 
 
 
 
 
Measure parathyroid hormone-related protein (PTHrP) and vitamin D metabolites
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
↑ serum phosphate
History of renal transplantation
 
 
 
↓/Normal phosphate levels
 
↑ Urinary calcium creatinine ratio
 
 
 
↓ Urinary calcium creatinine ratio
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Tertiary hyperparathyroidism
 
 
 
 
 
Primary hyperparathyroidism
 
 
 
 
 
Familial hypocalciuric hypercalcemia
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
PTHrP
 
 
1,25-dihydroxy vitamin D
 
 
25-hydroxy vitamin D
 
 
1,25-dihydroxy vitamin D
 
 
 
 
 
Normal PTHrP and vitamin D metabolites
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Humoral hypercalcemia of malignancy
 
 
Chest X-ray, ACE levels
 
 
Hypervitaminosis D
 
 
History of high milk intake,
excess calcium intake for treating osteoporosis or dyspepsia
 
Serum protein electrophoresis
 
Mammography
 
Check medications
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Check for malignancies
 
 
Bilateral hilar lymphadenopathy, ↑ ACE levels
 
 
 
 
 
 
 
Milk-alkali syndrome
 
Multiple myeloma
 
Breast cancer
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Sarcoidosis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Lithium induced hypercalcemia
 
 
 
Thiazide diuretic induced hypercalcemia
 

Hypocalcemia