OVERVIEW
Parathyroid disorders are a group of disorders characterized by systemic multi-system responses due to an increase or decrease in parathyroid hormone.
There are generally four parathyroid glands in humans, located in the posterior lateral walls of the thyroid gland, which mainly secrete parathyroid hormone (PTH), and the secretion of PTH is affected by the concentration of serum calcium ions, calcitonin, blood phosphorus, and blood magnesium. Common clinical parathyroid disorders include hyperthyroidism and hypothyroidism.
Causes
1. Hypoparathyroidism
Defects in any of the links between the glands or target cells, genetics, and surgical injury can cause this disease.
2. Pseudohypoparathyroidism
This disease is due to complete or partial absence of physiologic effects of PTH in peripheral tissues (kidneys and bone), or genetic defects.
3. Primary hyperparathyroidism
This disease is due to overproduction of PTH caused by parathyroid adenoma, hyperplasia or adenocarcinoma.
4. Secondary hyperparathyroidism
Vitamin deficiencies, gastrointestinal and hepatobiliary-pancreatic diseases, long-term phosphorus deficiency and hypophosphatemia, excessive calcitonin, pregnancy, lactation, cortisolism, etc., can cause this disease.
Symptoms
1. Hypoparathyroidism
The most characteristic clinical manifestation of hypocalcemia is episodic hypocalcemic convulsions on the basis of chronic hypocalcemia. Chronic hypocalcemia may have the following clinical manifestations.
(1) Psychoneurological system: due to increased neuromuscular excitability, epileptic seizures, hysterical seizures, neurasthenia, peripheral neuromuscular symptoms, autonomic symptoms, central nervous system symptoms.
(2) Eye: cataracts are more common in patients with chronic hypocalcemia, often bilateral, and their severity is related to the duration of hypocalcemia and blood calcium levels.
(3) Heart: Chronic hypocalcemia can cause persistent heart failure, hypotension, and resistance to digitalis and antihypertensive drugs. (4) Skin: Dry and flaky skin, brittle and brittle finger (toe) nails. Dermatitis in herpes-like pustulosis or pustular psoriasis is characteristic of hypocalcemia.
(5) Teeth: it can cause enamel hypoplasia and non-existence of permanent teeth.
(6) Blood system: hypocalcemia causes poor binding of vitamin B12 to endogenous factors, and macrocytic anemia may occur.
2. Hyperparathyroidism
(1) Hypercalcemia: the clinical manifestations involve multiple systems, and the appearance and severity of symptoms are related to the rate of elevation of blood calcium levels and the patient’s tolerance. Memory loss, emotional instability, apathy, personality change, lethargy, and weakness of limbs may occur.
(2) Skeletal system: Early stage of patients may have bone pain, mainly in the lumbar back, hip, ribs and limbs, with localized pressure pain. In the later stage, it is mainly manifested as fibrocystic osteitis, with bone deformity and pathologic fracture, short stature, difficulty in walking, and even bedridden, and some patients may have bone cysts, which is manifested as localized bone bulging.
(3) Urinary system: prolonged hypercalcemia may lead to polyuria, nocturia, thirst and other symptoms, and also kidney stones and calcification of renal parenchyma, repeated episodes of renal colic and hematuria, and urinary stones may induce urinary tract infection or cause urinary tract obstruction, which may affect renal function.
Examination
1. Hypoparathyroidism
Blood calcium decreases, blood phosphorus increases, blood ALP is normal or slightly low; blood magnesium may increase or decrease; urine calcium and phosphorus decrease; blood PTH decreases (hormone deficient), normal or elevated (hormone resistant). Imaging may reveal calcification of the basal ganglia, and bone density is often increased or normal. Electrocardiogram shows ST segment prolongation, QT interval prolongation and T wave abnormality, and electroencephalogram abnormality may occur.
2. Hyperparathyroidism
(1) Serum PTH＞100ng/L, blood calcium＞2.7mmol/L, blood phosphorus＜1.0mmol/L, urine calcium＞200mg/24h.
(2) X-ray shows thinning, thinning and deformation of bone, and multiple transparent cystic shadows in the bone.
(3) Ultrasound and CT are the preferred localization methods to show adenomas, and the finding of a posterior neck thyroid mass on examination helps in diagnosis and localization.
(4) Radionuclide scanning imaging of parathyroid glands can clarify the number and location of glands involved in the diseased parathyroid glands, and can understand whether there are ectopic parathyroid glands.
Diagnosis
1. Hypoparathyroidism
In patients with recurrent episodes of tetany, positive Chvostek’s sign and Trousseau’s sign, the diagnosis is basically confirmed if laboratory tests show a decrease in blood calcium and an increase in blood phosphorus, and renal insufficiency can be excluded.
2. Hyperparathyroidism
This disease should be suspected if one of the following features is present.
(1) Frequent active urinary stones or renal calcium deposits.
(2) Bone resorption, decalcification, or even cyst formation.
Treatment
The principle of treatment is to treat the cause of the disease, treat the symptoms, and choose surgical treatment according to the condition.