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Fluids, Electrolytes, and Acid/Base Disorders > Electrolytes > Flashcards

Electrolytes Flashcards

0
Q

Sx of hyponatremia

A

Nausea and malaise, stupor, coma

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1
Q

Sx of hypernatremia

A

Irritability, stupor, coma

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2
Q

Sx of hypermagnesia

A

Decreased DTRs, lethargy, bradycardia, hypotension, cardiac arrest, hypocalcemia

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3
Q

Sx of hypomagnesia

A

Tetany, arrhythmias, hypokalemia

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4
Q

Sx of hyperphosphatemia

A

Renal stones, metastatic calcifications, hypocalcemia

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5
Q

Sx of hypophosphatemia

A

Bone loss, osteomalacia

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6
Q

What are the systems most affected by hypercalcemia?

A

CV:

  • Short QT syndrome
  • Hypertension

Renal:

  • Nephrolithiasis
  • Diabetes insipidus
  • Renal insufficiency

Bone:
- Osteoporosis

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7
Q

What is the MCC of hypercalcemia? What causes that disorder?

A

Primary hyperparathyroidism is the MCC of hypercalcemia. It is caused by:

  • Solitary adenoma (80-85%)
  • Hyperplasia of all 4 glands (15-20%)
  • Parathyroid malignancy (1%)
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8
Q

What are the causes of hypercalcemia?

A

Primary hyperPTH and cancer account for 90% of hyperCa cases. Other causes are:

  • Vit D intoxication
  • Sarcoidosis and other granulomatous diseases
  • Thiazide diuretics
  • Hyperthyroidism
  • Multiple myeloma and metastases to bone
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9
Q

What is the Rx for hypercalcemia?

A

1) Saline hydration at high volume

2) Bisphosphonates: pamidronate, zoledronate

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10
Q

Two electrolyte imbalances that cause hypocalcemia

A

Hypermagnesia, hyperphosphatemia

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11
Q

Sx of hypercalcemia

A

Acute, symptomatic hypercalcemia presents with confusion, stupor, lethargy, and constipation.

Renal stones, bone pain, abdominal pain*, psychiatric overtones (anxiety, altered mental status); there is not necessarily calciuria

*“stones, bones and belly groans”

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14
Q

What are the Sx of hyperkalemia?

A

Potassium disorders interfere with muscle contraction and cardiac conduction. Look for:

  • Muscle weakness; paralysis when severe
  • Ileus (paralyzes gut muscles)
  • Arrhythmias
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14
Q

Sx of hypocalcemia

A

Signs of neuronal hyperexcitability in hypoCa:

  • Tetany (Trousseau sign)
  • Facial nerve hyperexcitability (Chvostek sign)
  • Seizures
  • Carpopedal spasm
  • Perioral numbness
  • Mental irritability
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14
Q

What are the causes of hypocalcemia?

A
  • Primary hypoPTH: most often a comp. of prior neck surgery e.g. thyroidectomy.
  • Hypomagnesemia: Mg is necessary for PTH to be released from the gland. Low Mg levels –> increased urinary Ca loss
  • Renal failure: the kidney converts Vit D to its active form

Less common causes:

  • Vit D deficiency
  • Fat malabsorption
  • Genetic disorders
  • Low albumin states
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14
Q

How does albumin affect Ca levels?

A

Low albumin causes a decrease in total serum calcium, but the free calcium is normal, so the pt is symptomatic.

For every point decrease in albumin, the calcium level decreases by 0.8

14
Q

What diagnostic tests are used to see if hypocalcemia is symptomatic? What are the findings?

A

EKG shows QT prolongation that may eventually cause arrhythmia.

Slit lamp exam shows early cataracts.

14
Q

What is the Rx for hypocalcemia?

A

Replace Ca and Vit D - orally if Sx are absent or mild, intravenously if Sx are severe.

14
Q

What are the 3 mechanisms that cause hyperkalemia?

A
  • Pseudohyperkalemia
  • Decreased excretion
  • Release of K from tissues
14
Q

What are the causes of pseudohyperkalemia?

A
  • Hemolysis
  • Repeated fist clenching with tourniquet in place
  • Thrombocytosis or leukocytosis will leak out of cells in the lab specimen

*None of these require further treatment or investigation beyond repeating the sample.

14
Q

What are the causes of hyperkalemia due to decreased excretion?

A

1) Renal failure
2) Aldosterone decrease:
- ACEIs or ARBs
- Type IV RTA (hyporeninemic, hypoaldosteronism)
- Spironolactone and eplerenone (aldosterone inhibitors)
- Triamterene and amiloride (other K-sparing diuretics)
- Addison disease

15
Q

What causes hyperkalemia due to release of K from tissues?

A
  • Any tissue destruction, such as hemolysis, rhabdomyolysis, or tumor lysis syndrome.
  • Decreased insulin
  • Acidosis: cells pick up H and release K in exchange
  • B-blockers and digoxin: inhibit the Na/K ATPase that drives K into cells
  • Heparin
16
Q

Besides looking at the potassium level, what test(s) must also be done for hyperkalemia? What are the findings?

A

EKG is the most urgent test in severe hyperkalemia, primarily because Rx is based on severity and hyperK is considered severe when their are findings on EKG, such as:

  • Peaked T waves
  • Wide QRS
  • PR interval prolongation
17
Q

What is the most important Rx for severe hyperkalemia? What else is used?

A

Severe hyperkalemia means there is an abnormal EKG. The first and most important Rx is calcium chloride or calcium gluconate because it stabilizes the cell membrane. The time of onset is only a few minutes. Other treatments include:

  • Insulin and D50W drive K+ into cells; onset 15-30 min
  • Bicarbonate is used when acidosis is the cause of hyperK; drives K+ into cells in exchange for H+; onset 15-30 min
  • Hemodialysis decreases total body K+ in cases of renal failure or life-threatening hyperK
18
Q

What are some less common ways to treat hyperkalemia?

A
  • B2-agonists e.g. albuterol can be used to drive K+ into cells; onset 30-90 min
  • Kayexalate decreases total body K+ by exchanging Na+ for K+ in the gut; onset 1-2 hours
  • Diuretics decrease total body K+; onset 30 min
19
Q

What are the Sx of hypokalemia?

A

HypoK leads to problems with muscular contraction and cardiac conduction. Potassium is essential for neuromuscular contraction. HypoK presents with:

  • Muscle weakness; paralysis if severe
  • Loss of reflexes
21
Q

What are the 4 mechanisms that cause hypokalemia?

A
  • Decreased intake - rare
  • Shift into cells
  • Renal loss
  • GI loss
22
Q

What are the causes of hypokalemia due to inadequate intake?

A
  • Alcoholism
  • Anorexia nervosa
  • Starvation
25
Q

What are the causes of hypokalemia due to shifting K+ into cells?

A
  • Alkalosis
  • Increased insulin
  • B-agonists
  • Vit B12 therapy
  • Lithium overdose
26
Q

What are the causes of hypokalemia due to GI loss?

A
  • Vomiting
  • Diarrhea
  • Villous adenoma
  • Laxative abuse
27
Q

What are the causes of hypokalemia due to renal loss?

A

1) Loop diuretics
2) Hypomagnesemia: due to opening of Mg-dependent K+ channels which spill K+ into urine
3) RTA types I and II
4) Increased aldosterone
- Primary hyperaldosteronism (Conn syndrome)
- Volume depletion
- Cushing syndrome
- Bartter syndrome: genetic disease causing salt loss at the loop of Henle
- Licorice

28
Q

What are the EKG findings in hypokalemia?

A

U waves are the most characteristic finding of hypoK. Other findings include:

  • Ventricular ectopy (PVCs)
  • Flattened T waves
  • ST depression
29
Q

What is the treatment for hypokalemia?

A

There is no maximum rate of oral K+ replacement because the GI system cannot absorb it faster than the kidneys can excrete it.

However, IV K+ replacement can cause fatal arrhythmia if it is done too quickly. Max dose is 40 mEq/L via peripheral IV; 100 mEq/L via central line. Infuse at 20 mEq/hr unless paralysis or ventricular arrhythmias are present.

**Also make sure to treat the underlying cause

Fluids, Electrolytes, and Acid/Base Disorders (3 decks)

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