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STEP1 > Calcium metabolism > Flashcards

Calcium metabolism Flashcards

1
Q

What is the explanation for hypercalcemia 90% of the time?

A
  1. Primary hyperparathyroidism

2. malignancy-secreting PTHrP

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2
Q

What is the most common form of primary hyperparathyroidism, producing hypercalcemia?

A

parathyroid adenoma

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3
Q

What is the second most common form of primary hyperparathyroidism?

A

parathyroid hyperplasia

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4
Q

Which types of malignancies can cause secretion of PTHrP and hypercalcemia?

A

small cell cancer (esp of lung)
renal cell carcinoma
breast mets to lung
multiple myeloma

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5
Q

10% of the time, what is the reason for hypercalcemia?

A 
lots of Vit D ingested
lots of Ca++ ingested
Granulomas: macrophages activate Vit D. THink TB, sarcoidosis
Increased bone turnover
Thiazide diuretics
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6
Q

Which types of things can cause increased bone turnover–leading to hypercalcemia?

A

hyperthyroidism
Vit A intoxication
immobilization

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7
Q

Which diuretics increase calcium in blood, which decrease it?

A

Loops lose calcium. Thiazides retain it.

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8
Q

What are the signs/symptoms of hypercalcemia/hyperparathyroidism?

A

Stones, Bones, Groans, Psychiatric Overtones

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9
Q

What types of stones are produced by hypercalcemia?

A

Kidney stones (ca++)
nephrocalcinosis
polyuria, polydipsia
uremia

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10
Q

What types of bone issues do you see with hypercalcemia?

A

osteoporosis
osteitis fibrosa cystica
osteoarthritis

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11
Q

What are the features of osteitis fibrosa cystica?

A 
subperiosteal bone respiration of the radial aspect of the middle phalanges
tapering of the distal clavicle
salt and pepper skull
bone cysts
brown tumors of the long bones
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12
Q

What are the abdominal groans of hypercalcemia?

A

constipation
N/V
peptic ulcers (increase in Ca++ causes an increase in gastrin)
pancreatitis

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13
Q

What are the psychiatric overtones of hypercalcemia?

A

lethargy
depression
psychosis
confusion, stupor, coma

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14
Q

What are other random features of hypercalcemia?

A

proximal muscle weakness
keratitis/conjunctivitis
HTN
itching

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15
Q

Which cells make parathyroid hormones?

A

chief/principal cells of parathyroid gland

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16
Q

What do the oxyphil cells of the parathyroid gland do?

A

no one knows!

they are packed with mitochondria, show up at puberty, and increase w/ age.

17
Q

How does PTH stimulate bone turnover?

A

stimulates osteoblasts. They release RANKL that stimulates osteoclasts

18
Q

Which carcinoma causes increased calcitonin?

A

medullary thyroid carcinoma
**not reactive to radioactive iodine treatments
C cells of thyroid aka parafollicular cells secrete calcitonin

19
Q

What is the nerve supply to the parathyroid gland?

A

cervical sympathetic ganglion

controls blood flow, but not stimulation

20
Q

What are the general causes of hypocalcemia?

A

Hypoparathyroidism
Vit D deficiency
acute pancreatitis

21
Q

What are some common causes of hypoparathyroidism?

A

parathyroidectomy
autoimmune
pseudohypoparathyroidism (kidney doesn’t respond to PTH)
Di George Syndrome

22
Q

Why does acute pancreatitis lead to hypocalcemia?

A

don’t get those fats dealt w/ w/o pancreatic secretions. Ca++ in gut combines w/ fatty acids–>soaps

23
Q

Chovstek and Trouseau signs are seen w/ hypo or hypercalcemia?

A

hypocalcemia

24
Q

What is a type of pseudohypoparathyroidism?

A

Type 1a: Albright Hereditary Osteodystrophy

25
Q

What are the special features of Albright Hereditary Osteodystrophy?

A

short stature and obesity
underdeveloped 3rd and 4th phalanges
osteitis fibrosa cystica

26
Q

Where are Ca++ and PO4 reabsorbed in the kidney?

A

Ca++–>DCT

PO4–>PCT

27
Q

Describe the relationship b/w magnesium and PTH secretion?

A

Low Mg++ –>PTH secretion

Super Low Mg–>Decreased PTH secretion

28
Q

What are some causes of low magnesium?

A 
Maggie and her DADA
diarrhea
aminoglycosides
diuretics
alcohol
29
Q

High PTH, High Ca++, Low phosphate…cause of hyperparathyroidism?

A

Primary hyperparathyroidism

most likely parathyroid adenoma

30
Q

high PTH, Low Ca++, High phosphate…cause of hyperparathyroidism?

A

Secondary hyperparathyroidism
chronic renal failure, can’t reabsorb anymore!

*can also be caused by Vit D deficiency-may get rickets

31
Q

What would the lab values and cause be for tertiary hyperparathyroidisM?

A

refractory chronic renal failure
parathyroid hyperplasia finally leads to a gland that secretes its own stuff constantly
High PTH, High Ca++

STEP1 (54 decks)

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