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GI Block > Endo: Calcium Disorders > Flashcards

Endo: Calcium Disorders Flashcards

1
Q

What 3 hormones regulate calcium levels?

What effect do they have?

A
  • PTH: increases serum Ca
  • Calcitriol: increases serum Ca
  • Calcitonin: decreases serum Ca
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2
Q

Name 3 ways that PTH raises serum Ca

A
  • Increased bone resorption
  • Increased calcium retention (and phosphate excretion) in kidney
  • increased calcitriol production in kidney, which increases gut absorption of Ca
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3
Q

What effect does PTH have on Ca and phosphate?

Compare this with Calcitriol’s effect.

A
  • PTH increases serum Ca and decreases serum phosphate
  • In contrast, calcitriol increases serum concentrations of BOTH
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4
Q

What cells release calcitonin?

What is its function?

A
  • Calcitonin is released by thyroid C cells
  • It inhibits bone resorption, decreasing serum calcium (“tones down ca”)
    • Minimal activity in normal homeostatis
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5
Q

If Calcium is elevated, what would PTH normally be?

A

PTH should be suppressed

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6
Q

What are the two main causes of primary hyperparathyroidism?

A
  • 1o hyperparathyroidism = elevated PTH due to
    • Adenoma (one of the parathyroid glands becomes overactive, other three become atrophied)
    • Hyperplasia (all four parathyroid glands become overactive)
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7
Q

What are the symptoms of primary hyperparthyroidism?

What are they caused by?

A
  • Stones: kidney stones
  • Thrones: polyuria
  • Bones: cystic bone spaces filled with brown fibrous tissue
  • Groans: weakness, constipation, abdominal pain
  • Psychiatric overtones

*All these symptoms are due to hypercalcemia

*But, hyperPTHism is usually asymptomatic!

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8
Q

Describe the PTH, Ca, Phos, and ALP levels expected in primary hyperPTHism

A
  • High PTH
  • High Calcium
  • Low Phosphate
  • High ALP
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9
Q

Describe the tumor associated with primary hyperPTHism

A
  • Cysts within bones filled with brown fibrous tissue (osteoclasts and deposited hemosiderin)
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10
Q

Compare the 2 syndromes associated with familial hyperPTHism.

A
  • MEN 1: pituitary adenomas, pancreas neuroendocrine tumors, parathyroid adenoma
    • Menin mutation
  • MEN 2A: parathyroid hyperplasia, pheochromocytoma, medullary thyroid cancer
    • RET mutation
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11
Q

What is secondary hyperPTH?

Most common cause?

A
  • Secondary hyperPTH: PTH is appropriately elevated PTH due to low serum calcium
    • normal, physiologic response
  • Usually associated with chronic renal disease (which causes low Vitamin D and elevated phosphate)
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12
Q

What causes familial hypocalciuric hypercalcemia?

What is the treatment?

A
  • Mutation in Calcium-sensing GPCR
    • Higher calcium levels are required to suppress PTH
  • NO TREATMENT NEEDED (simply have a higher calcium set-point)
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13
Q

Compare the 24 hr urine calcium levels in primary hyperPTH and familial hypocalciuric hypercalcemia

A
  • Primary hyperPTH: 24 hr urine calcium is high (b/c filtered Ca load overwhelms kidneys)
  • FHH: 24 hr urine calcium is low
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14
Q

What would the serum Ca, urinary Ca, and PTH be in familial hypocalciuric hypercalcemia?

A
  • Elevated serum calcium
  • Decreased urinary calcium
  • Elevated PTH
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15
Q

What two cancers are associated with hypercalcemia?

What would the serum PTH and Ca be in cancer-induced hypercalcemia?

A
  • Small cell lung cancer
  • Breast cancer
  • Low serum PTH (appropriately suppressed), high Ca
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16
Q

What are 3 ways cancer can cause hypercalcemia? (3)

A
  • PTH-Related Peptide production
  • 1,25 Vitamin D production
  • Bone metastases -> bone resorption
17
Q

Signs/symptoms of hypoparathyroidism (4)

A
  • Parasthesisa
  • Muscle cramps/weakness
  • Chvostek’s sign (tapping cheek causes contraction of facial muscles)
  • Trousseau’s sign (inflating BP cuff causes carpal spasm)
18
Q

What would the calcium, phosphate, and PTH be in hypoPTHism?

A
  • low PTH
  • low calcium
  • high phosphate
19
Q

What is the pathogensis of pseudohypoparathyroidism type 1A?

(defect, inheritance)

A
  • Kidneys are unresponsive to PTH
  • Due to autosomal dominant mutation in renal GPCR alpha subunit
  • Must be inherited from mother due to imprinting
20
Q

What are the physical signs of pseudohypoparathyroidism 1A? (3)

What is this called?

A
  • Shortened 4th/5th digits
  • Short
  • Obese
  • “Albright hereditary osteodystrophy”
21
Q

What are the PTH, Ca, and phosphate levels in pseudohyperPTHism 1A?

A
  • High PTH
  • Low calcium
  • High phosphate
22
Q

What would Ca, Phos, and PTH be in Vitamin D deficiency?

A
  • Low calcium
  • Low phosphorus
  • High PTH
23
Q

What is one lab and one x-ray finding suggestive of osteomalacia?

A
  • Elevated alk phos
  • Pseudofractures (Looser’s lines) on xray

Both suggest osteomalacia

24
Q

What would Ca and PTH be for…

primary hyperPTHism

secondary hyperPTHism

primary hypoPTHism

A
  • Primary hyperPTHism: High PTH, high Ca
  • Secondary hyperPTHism: High PTH, low Ca
  • Primary hypoPTHism: Low PTH, low Ca

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