Hyperparathyroidism

Summary

Hyperparathyroidism is a condition associated with elevated blood levels of parathyroid hormone (PTH). Depending on the pathogenesis of this condition, hyperparathyroidism can be defined as primary, secondary or tertiary. Primary hyperparathyroidism is an inherent disease of parathyroid glands associated with abnormal secretion of PTH. Secondary hyperparathyroidism results from abnormalities of calcium metabolism, which, if left untreated, can progress to tertiary hyperparathyroidism, which is associated with hypertrophy of the parathyroid gland and oversecretion of PTH even if the primary cause is eliminated. Diagnosis is based on biochemical parameters, which include serum PTH, calcium, and phosphate levels as well as urinary calcium. Management relies mostly on surgical parathyroidectomy for primary and tertiary hyperparathyroidism. Management of secondary hyperparathyroidism is focused on treatment of the underlying disease.

Definition

• Primary hyperparathyroidism (pHPT): Hypercalcemia results from abnormally active parathyroid glands.

هنا يكون السبب زيادة في نشاط الغدد جارات الدرقية، المشكلة تكون في الغدد نفسها فلذلك يتم افراز الهرمون مما يؤدي إلى زيادة في الكالسيوم

• Secondary hyperparathyroidism (sHPT): Hypocalcemia results in reactive overproduction of PTH.

السبب هنا هو نقص الكالسيوم، لذلك تدرك الغدد جارات الدرقية بأن الكالسيوم قد قل فتقوم بزيادة افراز الهرمون

• Tertiary hyperparathyroidism (tHPT): Hypercalcemia results from untreated secondary hyperparathyroidism, with continuously elevated PTH levels.

السبب هنا هو أنا المريض يعاني لفترة طويلة من Secondary hyperparathyroidism مما أدى إلى تحوله إلى Tertiary hyperparathyroidism

Causes

Primary hyperparathyroidism

• Parathyroid gland adenoma (∼ 85%): benign tumor of the parathyroid glands → most common cause of primary hyperparathyroidism
• Hyperplasia and multiple adenomas (∼ 15%)
• In rare cases, carcinomas ; (∼ 0.5%) or idiopathic
• MEN type 1 or 2
• Lithium

Secondary hyperparathyroidism

• Chronic kidney disease (most frequent cause)
• Malnutrition
• Vitamin D deficiency (e.g., reduced exposure to sunlight, nutritional deficiency, liver cirrhosis)
• Cholestasis (Bile is necessary for the absorption of fat in the intestines. Vitamin D3 is a fat-soluble agent and requires bile to be absorbed)

Tertiary hyperparathyroidism

• Due to long-standing secondary hyperparathyroidism
• Usually associated with end-stage kidney disease

Clinical features

Primary hyperparathyroidism

• Nonspecific: weakness
• Cardiovascular system: Left ventricular hypertrophy, Arterial hypertension, Shortened QT interval
• Kidney: Nephrolithiasis, nephrocalcinosis, Abdominal/flank pain, Polyuria, polydipsia
• Musculoskeletal system: Bone, muscle, and joint pain, Pseudogout
• Digestive tract: Nausea, constipation, Gastric or duodenal ulcers, Acute pancreatitis
• Psychological symptoms: depression, fatigue, anxiety, sleep disorders

Secondary and tertiary hyperparathyroidism

• Symptoms related to the underlying cause of sHPT (commonly renal failure)
• Bone pain and increased risk of fractures

Diagnosis