Electrolytes

Question 1

Causes of Hypercalcemia

Answer 1

Primary Hyper PTH - MEN1 or 2A

Cancer - PTHrP (squamous of head and neck, lung, breast, RCC)

Inc Ca absorption in GI - vit D overload, milk alkali syndrome (excessive Ca containing antacids)

Granulomas (Tb) - conversion to calciferol

HCTZ

Renal failure –> dec Ca reabsorption –> low Ca –> high
PTH (tertiary)

Inc Ca bone resorption - can be due to immobilization or Vit A overload or Pagets

Question 2

Hypercalcemia Work Up

Answer 2

Hx - meds, injury, diet

Check PTH level

If normal to high PTH - then primary hyperparathyroidism (likely adenoma); r/o FHH via 24 hr urine Ca level (low in FHH)

If low PTH - think malignancy

Question 3

Indications for Parathyroidectomy

Answer 3

• symptomatic

- asymptomatic but severe osteoporosis or renal problem in someone < 50 yo

Question 4

Hyponatremia Cause Breakdown

Answer 4

HYPOVOL

• Low urine Na
• Skin or GI losses, diuretics, mineralocorticoid def, 3rd spacing
• Tx is volume replacement w/ NS but slow to avoid demyelination

EUVOL

• SIADH (inappropriate water retention)
• Associated w/ malignancy, pulmonary infections, CNS problems
• Associated w/ SSRIs, MAOIs, TCAs, cyclophosphamide, vincristine, MDMA, neuroleptics, carbamazepine, NSAIDs, amiodarone, somatostatin
• Tx is fluid restriction and correct underlying problem

HYPERVOL

• Vol expansion due to dec renal excretion of water
• CHF, cirrhosis, nephrosis
• Tx is diuretic and fluid/Na restriction

Question 5

Causes of pseudo-hyponatremia

Answer 5

hyperglycemia, inc TGs, inc protein, lab error

Question 6

Hypernatremia Work Up

Answer 6

1- Check urine Osm

• High Osm (>400) - body can retain water so hypotonic losses
• Low Osm (<300) - central or nephrogenic DI

2- Treat underlying cause and replace water if needed (slow b/c cerebral edema)

Question 7

Causes and Signs of Hypokalemia

Answer 7

CAUSES
Dec intake
Renal losses - RTA I or II, Liddell, loops or HCTZ, any inc aldosterone
Extra-renal losses - vomiting, diarrhea, laxatives, Zollinger
Shift into cells - insulin, beta agonists, alkalosis

Signs - ST dep, U waves, musc aches and weakness, ileus
(Fear arrhythmia and resp failure)

Question 8

Causes and Signs of Hyperkalemia

Answer 8

CAUSES
Meds - ACE inhibitors, ARBs, K sparing diuretics
Shift out of cells - insulin deficiency, acidosis, burns
Dec renal excretion - retail failure, Addisons, RTA IV

-Signs - ascending flaccid paralysis, ileus, areflexia, weakness, peaked T waves and long QRS

Question 9

Tx Hyperkalemia

Answer 9

1- Ca gluconate - ASAP
2- IV insulin and glucose
3- Kayexcelate or loop diuretic (dialysis is last resort)
4- low K+ diet