Electrolytes Flashcards by Salvatore Liotta

How does aldosterone affect sodium

aldosterone causes:

increased sodium reabsorption
increased potassium excretion

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What is the most common electrolyte abnormality in hospitalized patients

hyponatremia

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What is the most common result of hyponatreamia?

Seizures

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What is pseudohyponatremia?

Serum Na is <135 but NORMAL osmolality due to hyperlipidemia and hyperproteinemia

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What is a common cause of redistributive hyponatremia?

hyperglycemia

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Euvolemic Hyponatremia: treatment

fluid restriction, treat underlying cause

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Euvolemic Hyponatremia: causes

SIADH
Primary polydipsia
Hypothyroidism
Adrenal Insufficiency

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What are the hallmark findings of SIADH?

-concentrated urine with low serum osmolality and euvolemia

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If a patient presents with hyponatremia, what are the first labs you would want?

UA -sodium
UA - osm
serum osm
CMP

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What should you do if a patient’s Na is less than 125?

Hospitalize!!

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Rapid increase in serum sodium can lead to what?

cerebral pontine myelinolysis

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Treatment of Hyponatreamia: rate of correction

First 24 hours: 6-12 mEq/L

First 48 hours: Less than 18 mEq/L in 48 hours

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How often should you check serum sodium when you are replacing to make sure you aren’t overcorrecting?

every 2 hours

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If a patient has low serum sodium and high serum osmolarity what is the most likely cause?

Hyperglycemia

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If a patient has high urine osmolarity and is hypervolemia what two things might you suspect?

2. Cirrhosis

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If a patient has high urine osmolarity and is euvolemic what might you suspect?

SIADH
Hypothyroid
Adrenal Insufficiency

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If a patient has high urine osmolarity and is hypovolemic and urine sodium is <10 what might be the cause?

vomiting or diarrhea

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If a patient has high urine osmolarity and is hypovolemic and has urine sodium >20 what might be the cause?

Adrenal insufficiency

Diuretics

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At what level is someone technically hypernatremic?

> 145mEq/L

What are the two causes of Diabetes insipidus?

Central DI - ADH isn’t being secreted

2. Nephrogenic DI - kidneys aren’t responding to ADH

What is the treatment for nephrogenic diabetes insipidus?

Thiazide diuretic**

How is water deficit calculated?

Normal Total Body Water - current Total Body Water

Where does regulation of renal K+ excretion take place in the nephron?

distal nephron

under the influence of aldosterone which increases sodium reabsorption and increases renal K+ excretion

Hypokalemia: clinical manifestations

Hyporeflexia*
Muscle cramps*
Weakness, fatigue
Flaccid paralysis (ascending)

Hypokalemia: ECG findings

- PVCs - Flattened T waves - Prominent U waves - Depressed ST segments

Name the causes of Hypokalemia (8)

- insulin - caffeine - bronchodilators - hyperthyroidism - Metabolic alkalosis - Diuretics*** - Cushing's - Vomiting or diarrhea

If a patient is low on potassium what is the best way to replace?

oral potassium replacement is preferred over IV as it has better absorption and won't damage vessels

Hyperkalemia - ECG

(in order of progression): - peaked T waves - Widened QRS - Junctional rhythm - Ventricular fibrillation

Name some causes of Hyperkalemia

- Drugs (ACE, ARB, K+ sparing diuretics, NSAIDs, Bactrim) - rhabdomyolysis - Acidosis - Decreased Insulin

Hyperkalemia: Emergent Treatment

1. IV calcium to stabilize membrane 2. Sodium Bicarbonate (increases pH, K+ is exchanged for H+ in the cells) 3. Insulin (add with sugar) 4. IV lasix

Hyperkalemia: not urgent

Kaexalate - exchanges sodium for potassium in the gut or Lasix (furosemide)

When calicum goes up ______ will go down

phosphate

ECF calcium

Free - 50% Protein bound - 40% Complexed - 10%

Serum calcium is impacted by what other substance?

albumin So, in hypoalbuminemia need to correct the measured calcium level

At what level is calcium considered Hypercalcemia?

Calcium >10.1

What are the symptoms of hypercalemia?

1. Kidney stones 2. Bone pain 3. Abdominal pain, N/V, constipation 4. Fatigue, lethargy, memory loss, psychosis 5. Decreased neuromuscular excitability

What will happen to the QT interval with Hypercalcemia?

shortened QT

What are the 2 biggest causes of hypercalcemia

1. Malignancy | 2. Primary hyperparathyroidism

Which medications can cause Hypercalcemia?

- Thiazide diurectics - Antacids - Lithium - Vitamin A analogs (Accutane)

Hypercalcemia: Treatment

1. Volume expansion - Normal saline!*** 2. Calcitonin 3. Pamidronate 4. Zoledronic Acid

Hypocalemia: clinical presentation

- Increased neuromuscular excitability (tetany)** - Parestheisas around lips, fingers and toes - Hyperreflexes - Chvostek's Sign - Trousseau's Sign

What are the cardiovascular effects of hypocalcemia?

1. Prolonged QT inverval, arrhythmia | 2. Hypotension

Hypocalcemia: Causes

1. Hypoalbuminemia 2. Large blood transfusion (citrate additives bind free calcium) 3. Hypomagnesemia (need Mg to help PTH work properly) 4. Hypoparathyroidism 5. Renal failure - retention of phosphate and reciprocal loss of Ca 6. Malabsorption/Vitamin D deficiency

What will happen to phosphate in refeeding syndrome?

Phosphate floods into cells and causes cell death

What two conditions do you need to first correct hypomagnesemia before you can fix them?

1. Ca++ | 2. K+