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3. Parathyroid disorders.pptx
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- 2. Embryology and anatomy •The superior parathyroid glands are derived from the fourth branchial pouch and the inferior glands from the third branchial pouches. • The position of normal superior parathyroid glands is more consistent, with 80% of these glands being found near the posterior aspect of the upper and middle thyroid lobes, at the level of the cricoid cartilage • The most common location for inferior glands is within a distance of 1 cm from a point centered where the inferior thyroid artery and RLN cross. • Approximately 15% of inferior glands are found in the thymus • The frequency of intrathyroidal glands is about 2%.
- 5. • Most individualshave four parathyroid glands. • The superior glands usually are dorsal to the RLN at the level of the cricoid cartilage, whereas the inferior parathyroid glands are located ventral to the nerve. • Appear golden yellow to light brown in adults. • Parathyroid color depends on cellularity, fat content, and vascularity. • Normal parathyroid glands are located in loose tissue or fat and are ovoid. • They measure up to 7 mm in size
- 7. • Arterial supplyis mainly by branches from the inferior thyroid artery, although branches from the superior thyroid artery supply at least 20% of upper glands. • Venous drainage is by ipsilateral superior, middle, and inferior thyroid veins. • Histologically, parathyroid glands are composed of chief cells, oxyphil cells and water-clear cells – all the three cell types have ability to secret PTH.
- 8. PHYSIOLOGY • Calcium isthe most abundant cation in human beings, and has several crucial functions. • Extracellular calcium levels are 10,000-fold higher than intracellular levels, and both are tightly controlled. • Extracellular calcium is important for excitation- contraction coupling in muscle tissues, synaptic transmission in the nervous system, coagulation, and secretion of other hormones. • Intracellular calcium is an important second messenger regulating cell division, motility, membrane trafficking, and secretion
- 9. • Hypoparathyroidism – Parathyroidtetany is due to hypocalcaemia – Etiology • Thyroidectomy • Parathyroid surgery • Maternal hypoparathyroidism -Newborn born to mother with undiagnosed hypoparathyroidism . – Symptoms appear in the first few days of life • Autoimmune disease
- 10. – Presentation • Thefirst symptoms are tingling and numbness in the face, fingers and toes • Cramps in the hands a - carpopedal spasm • Stridor • Latent tetany may be demonstrated by – Chvostek’s sign – Trousseau’s sign – Diagnosis • History • Low serum Ca++ level – Treatment • Calcium gluconate • Vitamin D • Magnesium supplements
- 11. • Hyperparathyroidism – PrimaryHPT is the third most common endocrine disorder, after diabetes mellitus and thyroid disease – Middle-aged and elderly women are most commonly affected by the disease – Hyperparathyroidism is associated with an increased secretion of parathyroid hormone
- 12. • Classification 1. Primaryhyperparathyroidism – There are elevated serum calcium and intact PTH (iPTH) levels – normal or increased urinary calcium – normal renal function – is due to parathyroid adenoma or hyperplasia, and very rarely carcinoma. – Ionizing radiation and familial predisposition – Lithium therapy ***In benign familial hypocalciuric hypercalcemia urinary calcium is low – a hereditary disease that cannot be corrected by parathyroidectomy
- 13. 2. Secondary hyperparathyroidism –is seen in the setting of chronic renal failure – In renal failure there is chronic hypocalcemia, which stimulates PTH secretion and parathyroid hyperplasia – Other less common causes of secondary HPT include malabsorption syndromes – All four glands are affected by hyperplasia 3. Tertiary hyperparathyroidism – in tertiary HPT there is autonomous hyperfunction and the parathyroids no longer respond to calcium feedback inhibition, which results in hypercalcemia.
- 14. • Acute hyperparathyroidism –Presents as nausea and abdominal pain followed by severe vomiting, dehydration, oliguria and finally coma. – The serum calcium is very high and leads to hypercalcemic crisis – Diagnosis is difficult and too often made after death – Treatment is urgent • Rehydration is vital. • Biphosphonates -(disodium etidronate and pamidronate) are specific inhibitors of bone resorption
- 15. • Clinical features –Hyperparathyroidism is commoner in women than men – Clinical features are enormously variable – Asymptomatic cases • The most common presentation is the detection hypercalcaemia by routine biochemical screening. – Nonspecific symptoms • Muscle weakness, thirst, polyuria, anorexia , weight loss
- 16. • Clinical features… –Bone disease - vague pains 1. Generalised decalcification 2. Single/multiple cysts, pseudotumour – Renal diseases 1. Renal stones 2. Nephrocalcinosis 3. Hypertension – Gastrointestinal Complications 1. Peptic ulcer disease 2. Pancreatitis 3. Cholelithiasis
- 17. • Clinical features… –Neuropsychiatric Complications 1. Psychosis, obtundation, or coma 2. Depression, anxiety, and fatigue 3. Electroencephalogram abnormalities – Other Features 1. muscle weakness 2. Chondrocalcinosis, gout, and pseudogout 3. Tissue calcium deposit (blood vessels, cardiac valves, and skin) 4. LVH
- 18. • Physical Findings –Palpable neck mass may be thyroid in origin or a parathyroid cancer – Corneal calcification – Band keratopathy – Fibro-osseous jaw tumors – Electrocardiographic changes with a shortened QT interval
- 19. • Differential diagnosis –Secondary cancer in bone (breast, prostate, bronchus, kidney and thyroid) – Carcinoma with endocrine secretion (bronchus, kidney and ovary) – Multiple myeloma – Vitamin D intoxication – Sarcoidosis – Thyrotoxicosis – Immobilisation – Medication: thiazide diuretics, lithium • Parathormone is not detectable in the blood in the above-mentioned conditions
- 20. • Laboratory Tests –Serum calcium ↑↑ – PTH assays(immunoradiometric assays) - N or↑ – Serum phosphorus - ↓ – Hyperchloremic metabolic acidosis – Alkaline phosphatase ↑ in bone diseases • Imaging tests – Hand and skull x-rays - may demonstrate osteitis fibrosa cystica – Abdominal ultrasound to document renal stones.
- 21. • Preoperative localisation 1.Non invasive – Ultrasound scan – Computerized tomography – Thallium-technetium isotope subtraction imaging – MRI 2. Invasive localization tests – FNAB – Angiogram – Venous sampling – Intraoperative PTH assay
- 22. • Treatment – Surgery– is the only corrective treatment – Postoperative vitamin D and calcium replacement therapy is required for varying periods
- 23. • Parathyroid carcinoma –Rare problem causing hyperparathyroidism – neck irradiation is a risk factor for the development of parathyroid adenomas not for carcinoma – Presents with severe symptoms, serum calcium levels >14 mg/dL, significantly elevated PTH levels (5 x normal) and a palpable parathyroid gland – Local invasion is most common – Tumor is gray-white to gray-brown intraoperatively • Treatment – Consists of bilateral neck exploration, with en bloc excision of the tumor and the ipsilateral thyroid lobe – Postoperative radiotherapy