Flashcards in Parathyroid Deck (39):
What is the phys of calcitonin release?
1. 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?
1. PTH secreted by chief cells of parathyroid gland
A. Parathyroid cells sense low serum Ca
2. PTH released → ↑ renal absorption of Ca → initiates conversion of Vit D to active form → intestinal absorption of dietary Ca → initiate bone resorption
3. 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
B. ↓ Plasma phosphate levels
What is hypoparathyroidism?
1. Inadequate secretion of PTH
A. ↓ Plasma calcium levels
B. ↑ Plasma phosphate levels
Define primary hyperparathyroidism
1. Overproduction of PTH → abnormal calcium homeostasis
2. F > M
A. Prevalence 1:1000 in US
3. Mean age 52-56yo
4. ↑ risk w/ age
5. ↑ in menopausal women
What is the most common cause of primary hyperparathyroidism?
1. 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?
1. PTH “shut-off” feedback is lost
2. Leads to excessive production of PTH
What are complications from primary hyperparathyroidism?
1. Leads to excessive resorption of Ca from bone
B. Osteitis Fibrosa Cystica (OFC) in severe cases
(diffuse demineralization, pathological fractures, and cystic bone lesions)
2. 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?
1. Most cases discovered incidentally by routine chemistry panel (hypercalcemia)
2. Symptoms:“bones, stones, abdominal groans, psychic moans, w/fatigue overtones”
What are the skeletal sxs of hyperparathyroidism?
1. Cortical bone loss
2. Bone & joint pain
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?
4. Rare nephrocalcinosis: calcification of kidneys
What are the abdominal sxs of hyperparathyroidism?
1. Abd pain
3. N/V -> dehydration
5. Peptic ulcers
6. Acute pancreatitis
What are the psychologic moans of hyperparathyroidism?
3. Inability to concentrate
4. Memory problems
What are the CNS manifestations of hyperparathyroidism?
1. Fatigue overtones
What are the neuromuscular manifestations of hyperparathyroidism?
1. Fatigue overtones
A. Muscle cramps
What are the cardiac manifestations of hyperparathyroidism?
1. fatigue overtones?
What are the CMP results in hyperparathyroidism?
1. inc Serum Calcium > 10.5 mg/dL
2. ↓ Serum Phosphate (PO4)
A. Normal 2.7-4.5 mg/dL
B. > 60 yr M 2.3-3.7 mg/dL
C. > 60 yr F 2.8-4.1 mg/dL
3. ↑ Alkaline Phosphatase only if bone turnover is present
A. M 38-126 U/L (nl)
B. F 70-230 U/L (nl)
5. Lipase/Amylase if abd pain
What are the PTH results of hyperparathyroidism?
↑ (or high normal), confirms Dx
What do you do if the pt has ↑ PTH & normal serum calcium?
1. Evaluate for 2°hyperparathyroidism (vit D or calcium deficiency, hyperphosphatemia, or renal failure)
2. If no secondary cause found:
A. Cont. monitoring
B. ≈ 19% will develop hypercalcemia over next 3 years
What do you do if the pt is positive for hyperparathyroidism?
1. Screen for Familial Benign Hypocalciuric Hypercalcemia (FBHH) w/ 24-hour urine for calcium & creatinine
2. Calcium excretion of < 50 mg/24 hr atypical for primary hyperparathyroidism & indicates possible FBHH
When are imaging studies used in hyperparathyroidism?
1. Not useful in the Dx of hyperparathyroidism
2. Parathyroid imaging is crucial in those w/ prior neck surgery
A. MRI preferred
3. Non-contrast CT scan of kidneys to determine calcium-containing stones
4. DEXA scan (bone density scan) to determine bone loss
What is the imaging study of choice for the neck?
What are the DDX for hyperparathyroidism?
1. Lab error, initially should be repeated ALWAYS
3. Malignant tumors (breast, lung, pancreas, uterus)
4. Multiple Myeloma, especially in elderly
6. Large consumption of calcium or vit D, especially w/ thiazide diuretics
7. Adrenal Insufficiency
8. Familial Benign Hypocalciuric Hypercalcemia (FBHH)
How are asymptomatic hyperparathyroid pts treated?
1. May not need therapy
2. Advise to keep active, avoid immobilization, & drink ↑ fluids
A. Thiazide diuretics
B. Large doses vit. A
C. Calcium-containing antacids
A. Serum calcium, albumin, BUN/Cr q 6 mo
B. Urine calcium annually
C. DEXA scan q 2 yr
What is 1st line treatment for symptomatic hyperparathyroidism?
What are the indications for parathyroid surgery?
1. Symptomatic, remove adenoma - majority are benign
2. NIH surgery criteria – for asymptomatic patients
A. Serum Calcium 1.0 mg/dL above normal range
B. 24hr urine Ca excretion > 400 mg
C. 30% reduction in creatinine clearance
D. Bone Mineral Density (BMD) T-score below - 2.5 any site
E. Age < 50 yr
What are the potential complications from parathyroid surgery?
1. Hypocalcemia (transient typical, can be permanent)
2. Injury to recurrent laryngeal nerve
5. Hyperthyroidism immediately after surgery
A. 2°to release of thyroid hormone during surgical manipulation of thyroid
B. Symptomatic pt may need propranolol/Inderal short-term
When are post parathyroid -surgery labs performed? What is checked?
1. 1-2 wks
2. Serum Calcium, Vit D level, PTH, (TSH, Free T4)
What is the non-surgical management for hyperparathyroidism?
2. Consider ERT in menopausal females (risk vs benefit)
A. Improve bone mineral density (BMD)
B. ↓ Serum calcium
3. Consider estrogen receptor modulators (raloxifene/Evista)
A. ↓ Serum calcium
4. Bisphosphonates (alendronate/Fosamax)
A. Improve BMD
5. Calcimimetic drugs (cinacalcet/Sensipar)
A. ↓ serum Ca
B No change in BMD
What is the emergency management of severe hypercalcemia?
1. IV volume replacement with NS
A. When volume restored give loop diuretic (furosemide/Lasix)
2. Calcitonin & bisphosphonate IV (zoledronic acid)
A. Temporary measure prior to surgery
What is hypoparathyroidism?
1. Insufficient secretion of PTH
A. Low serum calcium levels
B. High serum phosphate
C. Neuromuscular symptoms
What is the most common etiology of hypoarathyroidism?
1. Iatrogenic (surgery/radiation)
B. Laryngeal, or neck malignancy
What other etiologies for hypoarathyroidism exist?
1. Heavy Metal toxicity
A. Copper (Wilson Disease)
B. Iron (hemochromatosis)
2. Magnesium deficiency
A. Chronic alcoholism, malabsorption
A. Metastatic CA
A. Most common nonsurgical cause
What are most of the sxs of hypoarathyroidism caused by?
due to neuromuscular irritability
What are the sxs of hypoparathyroidism?
1. Paresthesia (fingers, toes, perioral)
2. Seizures (↑ w/ underlying seizure disorder)
3. Muscle cramps: low back, legs, feet
4. Muscle spasm: carpopedal, oral/facial (tetany)
5. Irritability, fatigue, anxiety, mood swings
7. Severe hypocalcemia can cause respiratory failure
A. Severe larynx spasm & bronchospasm
9. Nails thin, brittle
What is Chovstek's sign?
1. (+)Chvostek’s sign
2. Facial twitching near mouth induced by tapping facial nerve anterior to ear
What is trousseau's sign?
1. Carpal spasm (tetany) induced by BP cuff inflated to 20 mm/Hg above obliteration of radial pulse (takes 3-5 min)
What lab findings will be present in hypoparathyroidism?
1. ↓ Serum calcium ( 60 M 2.3-3.7 mg/dL
C. > 60 F 2.8-4.1 mg/dL
5. Serum albumin
6. ↓ Urinary calcium
7. Serum magnesium
8. Alkaline phosphatase WNL
A. M 38-126 U/L
B. F 70-230 U/L