Calcium disorders - McDermott

Question 1

Ddx for hypercalcemia

Answer 1

Account for 90%:
Primary hyperparathyroidism
Hypercalcemia of malignancy

Less common:
Thiazide excess
Familial Hypocalcuric Hypercalcemia
Vitamin D excess
Vitamin A excess
Acute renal failure
Hyperthyroidism

Question 2

What are the causes of primary hyperparathyroidism?

Answer 2

Primary hyperparathyroidism is oversecretion of PTH from the gland itself.

Parathyroid adenoma (>80%)
Parathyroid hyperplasia
Parathyroid carcinoma

Question 3

Describe the levels of PTH, Ca2+, PO4-, Alkaline phosphatase in chronic renal failure.

What is the pathophysiology

Answer 3

Decreased renal excretion of (PO4)2- causes levels to rise. PO4 binds Ca, lowering “free” levels. PTH senses low Ca and rises. Alk phos rises with the PTH level due to osteoblast activation of osteoclasts. SO;

PTH high
Ca low
PO4 high
Alkphos high

Question 4

What are the effects of vitamin D on

1) bone resorption
2) ca absorption (gut)
3) Phosphate absorption

Answer 4

1) bone resorption increases
2) ca absorption increased
3) phosphate absorption increases

Question 5

What is the term for the ringing of the iris that occurs in prolonged (>3 years) hypercalcemia?

Answer 5

Band keratopathy.

Question 6

What are some clinical signs/symptoms of hypercalcemia

Answer 6

MOST >50% are asymptomatic
Proximal muscle weakness
Lethargy
Psychiatric illness
Arthritis 
(Bones, moans, groans, stones)

Question 7

What are the mediators of hypercalcemia of malignancy?

Answer 7

PTH-RP
TNF
TGF-B
IL-1, IL-6
RANKL

Question 8

What is the Ddx for hypoparathyroidism

Answer 8

Primary hyperparathyroidism
Liver failure (due to loss of 25OH vitD)
Renal failure (due to loss of 1,25 OH vit d?)
Vitamin D deficiency
Pseudohyperparathyroidism (end organ resistance to PTH)
DiGeorge!
Hypoproteinemia (in a hospitalized patient. must correct Ca for the low protein)

Question 9

What are the clinical signs and symptoms of hypocalcemia?

Answer 9

Chvostek/Trosseau
cramps
Weakness
Parasthesias

Question 10

What are the expected lab values for a nutritional vitamin D deficiency? (PTH, Ca, PO4, vitD, alk phos)

Answer 10

PTH - High
Ca - Low
PO4 - Low
vit D - low (25OH)
ALK PHOS - HIGH

Question 11

Signs of vitamin D deficiency?

Answer 11

Bowing of long bones
Long bone pain
pseudofractures
pelvic narrowing

Question 12

What is a physical exam finding in pseudohypoparathyroidism? What is the name for the condition that causes this?

Answer 12

Shortened 4/5 metacarpals.

Albrights hereditary osteodystrophy.

Question 13

What is the underlying biochemical disfunction in pseudohyperparathyroidism

Answer 13

Mutation in the Gs alpha subunit, leading to decreased cAMP and decreased (re)action to PTH levels.