Fluid and electrolytes imbalances

Question 1

Hyponatremia

Answer 1

The most common electrolyte abnormality
Multiple causes and the first step in treating is determining the cause.
Evaluate:
1.) Urine sodium 10-20
2.) Serum osmolality 275-285
3.) Clinical status
Urine sodium helps distinguish renal from nonrenal causes

Question 2

Isotonic hyponatremia

Answer 2

Pesudohyponatremia serum osmo 284-294, usually a lab error.
Occurs with extreme hyperlipidemia or hyperproteinuria
Body water is normal and the pts are asymptomatic
Treatment includes cutting down fat (no fluid restriction)

Question 3

Hypotonic hyponatremia

Answer 3

Serum osmo <280
State of body water excess diluting all body fluids, clinical signs arise from water excess.
Needs to assess if pt is hypovolemic or hypervolemic
If hypovolemic, assess whether hyponatremia is due to extrarenal salt losses or renal salt wasting

1.) Hypovolemic with urine Na <10
-Dehydration, diarrhea, vomiting

2.) Hypovolemic with urine Na >20
-Diuretics
-ACE inhibitors
-Mineralcorticoid deficiency

3.) Hypervolemic, hypotonic hyponatremia
-Edematous states, CHF, liver disease, advanced renal failure
-RESTRICT WATER

Question 4

Hypertonic hyponatremia

Answer 4

Serum osmo >290
-Hyperglycemia, usually from HHS
-Osmo is high, Na is low

Question 5

Management of hyponatremia

Answer 5

Treatment is based on cause, treat underlying condition.
If hypovolemic, give NS
If urine Na >20, treat the cause
-If hypervolemic, implement water restriction
-If pt is symptomatic, give NS IV with loop diuretic
-If CNS symtpoms are present, consider 3% NS IV with loop diuretic

Question 6

Hypernatremia

Answer 6

Usually due to excess water loss, always indicates hyperosmolality (deficiency of water, >280).

Management depends on the cause:
-Severe hypernatremia with hypovolemia should be treated with NS followed by 1/2NS
-Hypernatremia with euvolemia should be treated with free water (D5W)
-Hypernatremia with hypervolemia should be treated with free water and loop diruetics, may need dialysis.

Question 7

Hypokalemia

Answer 7

Causes include chronic use of diuretics, GI loss, excess renal loss and alkalosis.
Elevated serum epinepherine in trauma pts may contribute to hypokalemia.

S/S:
-muscle weakness, fatigue, muscle cramps, constipation or ileus due to smooth muscle involvement.
-If severe, <2.5, may see flaccid paralysis, tetany, hyporeflexia and rhabdomyolysis.

Lab/diagnostics:
-Decreased amplitude on ECG
-Broad T waves
-Prominent U waves
-PVCs, Vtach, Vfib

Management:
-Oral replacement if >2.5 and no EKG abnormalities
-If <2.5 or s/s are present, give IV
-Give mag if K does not increases as mag frequently impaires K correction

Question 8

Hyperkalemia

Answer 8

Causes include excess intake, renal failure, drugs (NSAIDS), hypoaldosteronism and cell death.
Acidosis, K increases 0.7 with each 0.1 driop of pH.

S/S:
-Weakness, flaccid paralysis, adbominal distention, diarrhea

Lab/diagnostics:
-Tall peaked T waves

Management:
-Exchange resin (Kayexalate)
-10u insulin with D50
-Calcium

Question 9

Calcium

Answer 9

A major cellular ion and importatn as a mediator of neuromuscular and cardiac function.
Normal total calcium 8.5-10.5mg/dl or 2.2-2.6mmol/L
Normal ionized calcium 4.5-5.5mg/dl or 1.1-1.4mmol/L

Ionized calcium does not vary with albumin levels, this is useful to measure ical when albumin level is not wnl.
Acidemia increased ical and alkalemia decreased ical.
The amount of total calcium varies with the level of serum albumin, if there is a normal calcium level in the presence of a low albumin this suggests the pt is hypercalcemic.

Question 10

Hypocalcemia

Answer 10

Causes include hypoparathyroidism, hypomagnesemia, pancreatitis, renal failure, severe trauma, multiple blood transfusions.

S/S: Everything is hyper
-Increased DTRs
-Muscle/abdonimal cramps
-Trousseau’s sign
-Chvostek’s sign
-Prolonged QT
-Convulsions

Management:
- Check pH for alkalosis
- IV calcium gluconate if acute
- If chronic, oral supplements, vit D, aluminum hydroxide

Question 11

Hypercalcemia

Answer 11

Causes include hyperparathyroidism, hyperthyroididm, vit D intoxication, prolonged immobilization, thiazide diuretics.

S/S: low or sluggish
-Fatiguability
-Muscle weakness
-Depression
-Anorexia
-N/V
-Constipation
-Severe cases can cause coma or death.

Management:
-Calcitonin if impaired cardiovascular or renal function.
- May need NS with loop siuretic
- Dialysis for severe cases.

Question 12

Anion gap calculation

Answer 12

[Na+K] - [HCO3+Cl-]
Normal 7-17 (12 +/- 5)