Hypoparathyroidism Flashcards
what is the definition of hypoparathyroidism?
The disorder is caused by relative or absolute deficiency of plasma parathyroid hormone (PTH) synthesis and secretion. This leads to low albumin-corrected serum total calcium and elevated serum phosphate
what is the epidemiology of hypoparathyroidism?
rare
In adults, about 80% of cases of hypoparathyroidism are postsurgical with the remainder either of genetic or idiopathic aetiologies
what is the aetiology of hypoparathyroidism?
Postsurgical hypoparathyroidism is the major aetiology in adults - During thyroid surgery, one or more parathyroid gland(s) may be inadvertently removed or devascularized.
Genetic - DiGeorge syndrome, mutations in genes for extracellular calcium sensing pathway , mutations in transcription factors for parathyroid genes
what are the risk factors for hypoparathyroidism?
Thyroid surgery
Parathyroid surgery
Hypomagnesaemia
Moderate or chronic maternal hypercalcaemia
Autosomal dominant conditions
Hereditary haemochromatosis, transfusional iron overload, metastatic cancer
what is the pathophysiology of hypoparathyroidism?
Hypocalcaemia results from the deficient actions of parathyroid hormone (PTH) to reabsorb calcium from the urine, to generate sufficient 1,25-dihydroxyvitamin D in the kidney to absorb calcium from the gut, and to reabsorb calcium from bone. Hypocalcaemia, both acutely and chronically, produces irritability within the nerves leading to muscle cramping and stiffness, tetany, paresthesias, altered mentation, and even seizures. Chronic hypocalcaemia impairs left ventricular contractility.
what are the key presentations of hypoparathyroidism?
History or thyroid or parathyroid surgery Chronic alcoholism Malnutrition, malabsorption Muscle twitches and spasms Paraesthesias Poor memory Chvostek’s sign Convulsions Irregular heart beat Trousseau sign
what are the signs of hypoparathyroidism?
History or thyroid or parathyroid surgery Chronic alcoholism Malnutrition, malabsorption Chvostek’s sign Irregular heart beat Trousseau sign
what are the symptoms of hypoparathyroidism?
Muscle twitches and spasms
Paraesthesias
Poor memory
Convulsions
what are the first line and gold standard investigations of hypoparathyroidism?
Serum calcium - low Serum albumin - normal ECG - prolonged QT interval Plasma intact PTH - low Serum magnesium - low Serum 25-hydroxyvitamin D - low Serum phosphorus - elevated Serum creatinine - normal
what are the differential diagnoses for hypoparathyroidism?
Hypovitaminosis D, hypomagnesaemia, hypoalbuminemia, pseudohypoparathyroidism, renal failure
how is hypoparathyroidism managed?
Severe hypocalcaemia:
IV calcium, parenteral magnesium, treat resp alkalosis
Asymptomatic:
Oral calcium, low-dose calcitriol
Mild - moderate:
Oral calcium and calcitriol, human recombinant PTH (1-84), thiazide diuretic, oral magnesium, specific treatment for condition
how is hypoparathyroidism monitored?
If the patient stays overnight, serum calcium levels should be checked at least twice during the first 24 hours with the last measurement done the morning after surgery. If these serum calcium levels are normal or just mildly and transiently reduced, then the patient may be discharged with calcium supplements to be taken as needed.
If the patient has required intravenous calcium or has been symptomatic, then additional inpatient or outpatient monitoring may be warranted, depending on the circumstances. Calcitriol may be prescribed for outpatient use along with calcium supplements.
what are the complications of hypoparathyroidism?
Ectopic calcifications, cataract, hypercalcaemia, renal insufficiency, renal stones
what is the prognosis of hypoparathyroidism?
No long term data, excellent for patients with temporary hypoparathyroidism
