Parathyroid Flashcards
What is the phys of calcitonin release?
- Parafollicular cells (C-cells) of thyroid gland secrete calcitonin in response to high Ca levels, this counteracts effects of PTH
What is the phys of PTH release?
- PTH secreted by chief cells of parathyroid gland
A. Parathyroid cells sense low serum Ca - PTH released → ↑ renal absorption of Ca → initiates conversion of Vit D to active form → intestinal absorption of dietary Ca → initiate bone resorption
- Decreases renal absorption of phosphorus, lowering serum phosphate level
What is hyperparathyroidism?
1. Excessive secretion of PTH A. ↑ Plasma calcium levels 3. Excessive excretion of phosphorus A. Phosphaturia B. ↓ Plasma phosphate levels
What is hypoparathyroidism?
- Inadequate secretion of PTH
A. ↓ Plasma calcium levels
B. ↑ Plasma phosphate levels
Define primary hyperparathyroidism
- Overproduction of PTH → abnormal calcium homeostasis
- F > M
A. Prevalence 1:1000 in US - Mean age 52-56yo
- ↑ risk w/ age
- ↑ in menopausal women
What is the most common cause of primary hyperparathyroidism?
- Most caused by single parathyroid adenoma
A. Chief Cell Adenomas 85% of all cases
B. Some multiple adenomas
C. Etiology of most adenomas unknown
D. Some familial as part of Multiple Endocrine Neoplastic syndromes (MEN 1 and 2)
What is the pathophys of primary hyperparathyroidism?
- PTH “shut-off” feedback is lost
2. Leads to excessive production of PTH
What are complications from primary hyperparathyroidism?
- Leads to excessive resorption of Ca from bone
A. Osteopenia
B. Osteitis Fibrosa Cystica (OFC) in severe cases
(diffuse demineralization, pathological fractures, and cystic bone lesions) - Leads to renal tubular reabsorption of calcium
A. Predisposes to formation of renal stones
B. ↑ Ca in filtrate results in hypercalciuria
What is the clinical presentation of hyperparathyroidism?
- Most cases discovered incidentally by routine chemistry panel (hypercalcemia)
- Symptoms:“bones, stones, abdominal groans, psychic moans, w/fatigue overtones”
What are the skeletal sxs of hyperparathyroidism?
- Cortical bone loss
- Bone & joint pain
- Pseudogout
A. Chondrocalcinosis- Calcium phosphate deposition
B. Crystal deposits in joints on X-ray
C. Streaking of soft tissue w/ calcium
What are the renal manifestations of hyperparathyroidism?
- Nephrolithiasis
- Polyuria
- Hypercalciuria
- Rare nephrocalcinosis: calcification of kidneys
What are the abdominal sxs of hyperparathyroidism?
- Abd pain
- Anorexia
- N/V -> dehydration
- Constipation
- Peptic ulcers
- Acute pancreatitis
What are the psychologic moans of hyperparathyroidism?
- Subtle
- Depression
- Inability to concentrate
- Memory problems
What are the CNS manifestations of hyperparathyroidism?
- Fatigue overtones
A. Malaise
B. Irritability
C. Insomnia
What are the neuromuscular manifestations of hyperparathyroidism?
- Fatigue overtones
A. Muscle cramps
B. Weakness
C. Paresthesia