Endocrine Disorders: Parathyroid Glands

Endocrine Disorders: Parathyroid Glands

• Parathyroid glands are small endocrine glands located in the neck, typically four in number, on the back of the thyroid gland
• They produce parathyroid hormone (PTH)
• PTH plays a crucial role in regulating blood calcium levels (9-11 mg/100 ml) and calcium within bones.

Mode of Action of Parathyroid Hormone (PTH)

• Increases calcium absorption from the gastrointestinal tract (GIT)
• Increases calcium reabsorption from the kidneys
• Stimulates osteoclastic activity, releasing calcium from bones
• Increases phosphate excretion from the kidneys
• Increases the synthesis of vitamin D (1,25-dihydroxycholecalciferol), aiding calcium absorption from the GIT

Calcium Function in the Body

• A component of bone and teeth structure
• Essential for blood clotting, muscle contraction, and nerve function

1- Hypoparathyroidism: Etiology

• Accidental surgical excision during thyroid surgery
• DiGeorge syndrome (congenital absence of parathyroid gland)
• Autoimmune destruction of parathyroid glands
• Radiation therapy to the neck
• Metastatic cancers
• Infections

Clinical Features of Hypoparathyroidism

• General Manifestations: Occur when serum calcium levels fall below 7 mg/100 ml. Includes nausea, vomiting, paresthesia (numbness and tingling), muscle cramps, irritability, and tetany.
• Trousseau's sign: Carpopedal spasm brought about by reduced blood flow to the hand.
• Chvostek's sign: Twitching of facial muscles when the facial nerve is tapped
• Oral Manifestations: Enamel hypoplasia, abnormal dentin formation, delayed tooth eruption, wide pulp chambers, and short roots

Diagnosis of Hypoparathyroidism

• Low serum calcium levels
• Elevated serum phosphorus levels

Dental Implications of Hypoparathyroidism

• Arrhythmia and heart block may result from low calcium levels.
• Increased risk of caries due to hypoplastic teeth.
• Frequent oral care is crucial in patients with hypoparathyroidism for hypoplastic teeth to prevent complications
• Emergency treatment for tetany: Intravenous calcium lactate injection (10-30 ml of 10% solution)

2- Hyperparathyroidism: Etiology

• Primary: Parathyroid gland enlargement (adenoma)
• Secondary: Resulting from low calcium levels due to conditions like kidney failure, malabsorption, or prolonged dialysis
• Tertiary: Parathyroid gland tissue becomes unresponsive to blood calcium levels, usually resulting from long standing secondary cases

Clinical Features of Hyperparathyroidism

• General Manifestations: Affecting the bones, kidneys, and gastrointestinal tract.
• Bone: Generalized osteoporosis, osteitis fibrosa cystica (bone replaced with fibrous tissue), giant cell lesions (brown tumors), bone pain, and pathological fractures
• Kidney: Renal stones, hematuria, urinary tract infections, renal hypertension
• Gastrointestinal tract: Anorexia, nausea, vomiting, peptic ulcers, and crampy pain
• Oral: Bone abnormalities (general manifestations), loss of lamina dura, teeth looseness and drifting, and giant cell granulomas (brown tumors)
• Radiographic Features: Cortical bone resorption, rarefaction, loss of trabecular structure, ground glass appearance, and thinning or loss of cortical bone.

Dental Implications of Hyperparathyroidism

• Oral manifestations can complicate dental management due to decreased bone density and other oral features.
• Peptic ulcers, renal failure, and bone fragility can also be complications impacting dental treatment and subsequent recovery.

This quiz focuses on the functions and disorders of the parathyroid glands, particularly emphasizing parathyroid hormone (PTH) and its role in calcium regulation. It covers the mode of action of PTH and the implications of hypoparathyroidism. Test your knowledge about these critical endocrine functions.