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DEMS Unit 3 > Disorders of Ca2+ metabolism > Flashcards

Disorders of Ca2+ metabolism Flashcards

1
Q

Ca2+ range

A

8.5 mg/dl - 10.5 mg/dl

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2
Q

Ca2+ regulating hormones

A
  1. PTH
    - made in parathyroid
  2. 1,25(OH)2D3
    - made in kidney
  3. Calcitonin
    - made in thyroid
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3
Q

Ca2+ regulating organs

A
  1. bone
  2. kidney
  3. intestine
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4
Q

PTH effects

A

↓ Calcium excretion

↑ bone resorption
↑ Ca2+ abs
↑ 1,25 OH2D production
↑ Phosphate excretion

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5
Q

Major storage form of Vit D

A

25OHVIt D

(it gets converted to active form 1,25 OH2 Vit D by kidney

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6
Q

Effects of 1,25(OH)2VitD

A

↑ Bone resorption → ↑ serum ca → ↑Ca absorption + ↑ Phosphate absorption

*note that PTH effects is ↑ phosphate excretion

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7
Q

What do these cells regulate?

  1. Parathyroid cell
  2. Parafollicular C cell
  3. Renal tubular cell
A
  1. Parathyroid cell
    - PTH secretion
  2. Parafollicular C cell
    - Calcitonin secretion
  3. Renal tubular cell
    - calcium excretion
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8
Q

SOme causes of hypercalcemic disorders

A

LOTS! (12)

  1. primary hyperparathyroidism
  2. Familial hypocalciuric hypercalcemia
  3. granulomatous disease
  4. VIt D intox
  5. Vit A intox
  6. hyperthyroidism ect
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9
Q

Of the 12 hypercalcemic disorders, when would you expect ↑ PTH levels?

A

primary hyperparathyroidism

Familial hypocalciuric hypercalcemia

*labs are exactly same. need to differentiate via piss

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10
Q

Classifications of primary hyperparathyroidism

A
  1. 85% adenoma
  2. 15% hyperplasia
    - usually familial
    3.
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11
Q

Clinical features of primary hyperparathyroidism

A

> 50% asymptomatic

If severe
Bones, Stones, Groans, Moans syndrome

  1. Skel disease
  2. kidney disease
  3. muscle weakness
  4. arthritis
  5. HTN
  6. Band keratopathy
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12
Q

Band keratopathy

A

seen in hyperparathyroidism

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13
Q

labs to dx primary hyperparathyroidism

A
  1. ↑ serum Ca2+
  2. ↓ serum phosphate
  3. ↑ serum PTH
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14
Q

is primary hyperparathyroidism due to sporadic or familial causes?

A

90% sporadic
10% familial
- familial HPT
- MEN I + IIA

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15
Q

MEN I germline can cause

A

3 P’s (337)

Pituitary tumors
Parathyroid Hyperplasia
Pancreatic Islet tumors

  • MENIN gene mutation
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16
Q

MEN IIA germline can cause

A

2 P’s

Pheochromocytoma
Parathyroid hyperplasia
Medullary thyroid carcinoma

  • RET gene mutation
17
Q

Secondary hyperparathyroidism

A

parathyroid glands become active on their own

  • Secondary hyperplasia due to ↓ Ca2+ abs and/or ↑ PO43-,
    most often due to chronic renal disease!!!!
    (↓ 1, 25 Vit D)
    or nutritional vit defic.
18
Q

Labs of secondary hyperparathyroidism

A
  1. ↓ Ca2+
  2. ↑ Phosphorous
  3. ↓ 1, 25 Vit D (most often due to chronic renal disease)
19
Q

1 mediator of hypercalcemia of malignancy

what lab values would you expect?

A

PTH related peptide (PTH-RP)

↓ serum PTH
↑ serum Ca2+
↑ PTH-RP

20
Q

Familial hypocalciuric hypercalemia

- what lab values will you see?

A

Have inactivating mutations in Ca2+ sensor receptor
- body will compensate and ↑ PTH secretion +
↓ Ca2+ excretion

labs:
↓ Urinary Ca2+
↑ Serum PTH + Ca2+

21
Q

All causes of hypocalcemia will have a ↑ serum PTH except which one?

A

↓ PTH if pt has hypoparathyroidism

22
Q

Corrected serum total calcium

A

measure if you see that serum ca2+ is low

Add 0.8 mg/dl to total calcium for every 1 g/L Albumin is

23
Q

Clinical features of Hypocalcemia

A
  1. paresthesias
  2. muscle cramps
  3. muscle weakness
  4. chvostek’s sign
    - tap facial nerve, wink on that side of face above lips
  5. Trousseau’s sign
    - make duck with hand if you put a bp cuff on
24
Q

what do you think when both Ca and Phos are low?

A

VIt D deficiency

  • osteomalacia
  • changes both in the same direction
25
Q

Vit D dependent rickets Type 1

A

Congenital 1 alpha hydroxylase deficiency

- cant make active Vit D (low 1,25, high 25)

26
Q

Vit D dependent rickets Type 2

A

congenital vit D receptor deficiency/not working

  • have nl levels of Vit D and everything down stream
  • give them high enough levels, then they WILL respond
27
Q

Lab values for nutritional vit D deficiency

A

Serum:
↓ Ca2+
↓ Phosphate
↓ 25 (OH) VIt D

↑ PTH
↑ Serum alkaline phosphate (suggesting osteomalacia)

28
Q

lab values for hypoparathyroidism and pseudohypoparathyroidism

A

hypoparathyroidism
↑ serum phosphate
↓ serum ca
↓ serum PTH

pseudohypoparathyroidism
↑ serum phosphate
↑ serum PTH
↓ serum Ca

  • note that pseudohypoparathyroidism can result in short 4th and 5th metacarpals
  • *pseudopara: PT receptors in kidney and bones are not responsive to PTH itself. PTH mech doesnt work. Give Vit D.
  • give Vit D
29
Q

PTH endocrine signaling pathway

A

activate alpha subunit of GPCR → cAMP → PTH action

30
Q

Albrights hereditary osteodystrophy

A

Pseudohypoparathyroidism
- can result in short 4th and 5th metacarpals

↑ serum phosphate
↑ serum PTH
↓ serum Ca

  • pseudopara: PT receptors in kidney and bones are not responsive to PTH itself. PTH mech doesnt work. Give Vit D.
  • give Vit D since they cant make active Vit D

DEMS Unit 3 (26 decks)

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