Calcium Disorders & Primary Hyperparathyroidism

Question 1

Primary Hyperparathyroidism

Answer 1

3rd most common endocrine disorder after DM and thyroid disorders
Results from overproduction of the parathyroid hormone
Incidence is rare ~1%, increases to 2% after age 55

Question 2

Risk Factors

Answer 2

More common in women
Risk factors: 
postmenopausal women
> 60 yrs
multiple endocrine neoplasia

Question 3

Clinical Presentation

Answer 3

Usually no obvious sx
Mild sx: nonspecific complaints: aching and depression
Severe or advanced disease: bone pain, osteoporosis, skeletal muscle weakness, renal calculi
Dx usually made by routine lab work

Question 4

Symptoms of Excessive Ca Levels

Answer 4

Stones - kidney stones
Bones - bone disease, Fx
Abdominal moans GI upset
Psychic groans - confusion

Question 5

Parathyroid Physiology

Answer 5

4 Parathyroid glands
Function: calcium homeostasis (Ca necessary for nerve, bone and muscle fxn)
Secrete PTH in response to alterations in serum calcium levels to raise serum calcium
PTH stimulates:
calcium reabsorption in distal tubule of kidney
osteoclast resorption in bone
synthesis of 1,25-Dihydroxy-vit D
enhances increased calcium absorption in sm intestine
Elevated calcium – shuts down PTH production

Question 6

PHPT

Answer 6

Parathyroid loses ability to regulate PTH secretion
Overproduction of PTH
Leads to
enhanced bone resorption of calcium and phosphorous
intestinal absorption of calcium
renal tubular reabsorption of calcium
Results in Hypercalcemia

Question 7

Causes

Answer 7

Parathyroid adenoma 80-90%
Multiple adenomas, parathyroid hyperplasia 10-20%
Parathyroid carcinoma – 1%
Other: multiple endocrine neoplasia

Question 8

Dx

Answer 8

Lab: Serum Parathyroid Hormone (PTH) level
Normal or low level – not PHPT
Elevated calcium and elevated PTH level = PHPT dx
25OH vit D level
Low vit D level - counteract high calcium levels
Replace Vit D with Vit D3

Question 9

Potential Results of Untreated PHPT

Answer 9

Bones: decreased BMD, osteoporosis, fractures
Cardiac: HTN, Short QT interval and prolonged PR
Psych: fatigue, apathy, depression, mood swings, irritability
Ca > 13mg/dL: n, v, dehydration, abd pain, muscle weakness, shortened QT interval, arrthymias, renal failure, coma, death

Question 10

DD

Answer 10

Familial hypocalciuric hypercalcemia
Malignancy: lung, breast, Multiple Myeloma 
 Meds
Hyperthyroidism
Adrenal insufficiency
Chronic renal failure

Question 11

PHPT vs Malignancy

Answer 11

PHPT - elevated serum PHT level

Malignancy - Low to normal serum PTH, Markedly elevated calcium >14, Skeletal and renal abnormalities - severe

Question 12

Drug Induced Hypercalcemia

Answer 12

Lithium
Thiazide diuretics
Calcium antacids
Vitamin intoxication
Calcium supplements
In vulnerable individuals

Question 13

PHPT Tx

Answer 13

Parathyroidectomy is curative
Criteria for parathyroidectomy: (NIH consensus document 1990)
Serum calcium > upper limits of normal (norm = 8.5-10.2)
Ccl < 60
Age < 50
T <2.5, or fagility fx
Consistent FU unlikely

Question 14

Next step after PHPT DX

Answer 14

Refer to Endo

Question 15

Hypocalcemia

Answer 15

Due to Hypoalbuminemia
Medical calculators – corrected calcium formula
Ca 7.8 mg/dL, Albumin 3.0g/L=
Corrected Ca 8.6 mg/dL
Ionized calcium is most accurate measure of calcium

Question 16

Common Causes of Hypocalcemia

Answer 16

Advanced CKD - decreased production of active vit D3, elevated phosphate
Primary hypoparathyroidism - d/t mutations in Ca sensing receptor -> inapropriate suppression of PTH -> hypoCa
Magnesium depletion - can reduce PTH and Ca
Vitamin D Deficiency

Question 17

Hypocalcemia Tx

Answer 17

Calcium supplement
Restore Vitamin D
Improve nutrition
Endocrine referral
Nephrology referral – CKD