Parathyroid Disorders Flashcards
Parathyroid glands are responsible for
Regulating calcium levels in the blood through a negative feedback system involving the gut, kidneys, and bones
Risk factors for primary hyperparathyroidism (most common type)
Neck radiation, age >50, female sex (2:1), multi glandular hyperplasia, or family history of MEN-1 and MEN-2a (both uncommon)
Secondary hyperparathyroidism occurs due to
Decreased levels of 1,25-dihydroxyvitamin, hyperphosphatemia, and hypocalcemia in presence of CKD or
Vitamin D deficiency due to poor diet, lack of sun, malabsorption, liver disease, or other chronic illnesses
Tertiary hyperparathyroidism is the progression of parathyroid hyperplasia due to
Autonomous over production of PtH causing hypercalcemia
Symptoms of hyperparathyroidism
“Bones, stones, groans, and psychiatric overtones”
- osteoporosis, bone pain
- kidney stones; excessive urination
- ulcers, constipation, abdominal pain
- fatigue, depression, forgetfulness, weakness
Diagnostics of hyperparathyroidism
-hypercalcemia on more than 1 serum measurement
-check ionized calcium, albumin, PTH, creatinine, and 25-hydroxyvitamin D
-24-hr urine calcium and creatinine to distinguish from familial hypocalciuric hypercalcemia (FHH)
-BMD (DEXA scan)
Findings in primary hyperparathyroidism
-elevated immunoreactive PTH (intact PTH)
-persistent hypercalcemia (if severe, consider parathyroid cancer)
-may need outpatient nuclear scanning (Sestamibi scan)
Risk factors for benign adenomas
Genetic disorders, lithium, CKD, women >60, radiation to head/neck
Parathyroid cancer should be considered if
Hypercalcemia is >14, serum PTH >2x normal, a cervical mass is palpated in a hypercalcemic patient, there is unilateral vocal cord paralysis, or renal and skeletal disease are noted in a patient with a markedly elevated PTH
Normal serum calcium and PTH levels
Serum calcium 8.5-10.4
PTH 10-65
Chronic renal failure is associated with hypo-vitamin D, hyperphosphatemia, and hyperparathyroidism. What should be monitored?
-calcium
-creatinine
-UA
-PTH
(every 3 months)
Medical treatment for high risk patients with hyperparathyroidism
Calcium salts (which also bind phosphorous) and vitamin D
In mild hyperparathyroid disease, what should be monitored?
-calcium
-creatinine
-UA
-PTH
(every 6-12 months)
-bone density (every 12 months)
The goal of oral calcium should be
1g/day or less
What are factors that aggravate hypercalcemia, that should be avoided?
Thiazide diuretics, lithium, prolonged bed rest or inactivity
Preventive measures of hyperparathyroidism
-physical activity to minimize bone resorption
-drink 8 glasses water/day to minimize risk of nephrolithiasis
-maintain moderate calcium intake (1000mg/day) as a low calcium diet may lead to further increases in PTH secretion and could aggravate bone disease
-maintain moderate vit D intake (400-600 IU daily)
If serum calcitriol levels are high, then restrict to
<800mg/day
Vitamin D deficiency stimulates
PTH secretion and bone resorption
Causes of hypocalcemia/hypoparathyroidism
-parathyroidectomy (inadequate PTH secretion)
-hypoalbuminemia
-vitamin D deficiency
-abnormal magnesium metabolism
-extravascular deposition of calcium
-medications
-genetic causes
-autoimmune conditions
Symptoms of hypocalcemia/hypoparathyroidism
-peripheral nervous system: numbness, paresthesias, muscle stiffness, and cramps, fasciculations, and tetany
-cardiovascular system: decreased contractility, QT-prolongation, vasodilation that can result in CHF, dysrhythmia, rarely - hypotension
Medications/compounds that suppress the release of PTH
Aluminum, asparaginase, doxorubicin, cytosine arabinoside, cimetidine, alcohol, aminoglycosides, cisplatin, pentamidine, digoxin, amphotericin B
Diagnostic work-up for hypoparathyroidism
-repeat calcium measurement for confirmation and measure serum albumin concentration (calcium is bound to albumin)
-if abnormal, check an ionized (free) calcium level for accuracy
-serum magnesium and phosphate levels
Treatment for hypoparathyroidism
-IV calcium for symptomatic patients and those with serum corrected calcium of <7.5
-PO calcium for mild disease (1500-2000mg of Carbonate or Citrate) in divided doses
-vitamin D deficiency - calcium supplementation with addition of vit D2 or D3 (50,000 IU weekly for 6-8 weeks)
-hypomagnesemia - IV mag sulfate until level is >0.8