Electrolyte Disturbances - Renal - Medbullets Step 2/3

Snapshot

A 56-year-old man is brought to the emergency department by his son due to mild confusion and shortness of breath. Prior to symptom develop he needed to sleep on a recliner due to feeling short of breath while supine. Medical history is significant for chronic obstructive pulmonary disease and a prior myocardial infarction requiring coronary artery bypass grafting. On physical exam, the patient is altered but able to follow commands. There is jugular venous distension, an S3 heart sound, and 2+ lower extremity pitting edema. Laboratory testing is significant for a brain natriuretic peptide 950 pg/mL and serum sodium of 130 mmol/L. (Hyponatremia secondary to congestive heart failure)

Potassium

Electrolyte Disturbances
Hyponatremia	Hypernatremia
Definition serum sodium of < 135 mmol/L Etiology pseudohyponatremia hyperglycemia hyperlipidemia hypervolemic hyponatremia congestive heart failure nephrotic syndrome cirrhosis renal insufficiency hypovolemic hyponatremia vomiting and diarrhea burns sweating cystic fibrosis diuretic use (e.g., thiazides) angiotensin converting enzyme (ACE) inhibitor adrenal insufficiency euvolemic hyponatremia psychogenic polydipsia hypothyroidism syndrome of inappropriate anti-diuretic hormone (SIADH) diuretic use ACE inhibitors Presentation stupor coma seizures nausea malaise Studies assess volume status serum electrolyte and urine studies Treatment address underlying cause asymptomatic free water restriction moderate hyponatremia IV normal saline loop diuretics may be added severe hyponatremia hypertonic (3%) saline Complications rapid correction of hyponatremia can lead to osmotic demyelination syndrome	Definition serum sodium of > 145 mmol/L Etiology insensible losses (e.g., sweating) osmotic diarrhea osmotic diuresis e.g., diabetic ketoacidosis poor fluid intake diuretic use osmotic diuresis vomiting and diarrhea central and nephrogenic diabetes insipidus hypertonic sodium gain Presentation stupor coma seizure Studies assess volume status serum electrolyte and urine studies Treatment address underlying cause intravenous (IV) 5% dextrose in water (D5W) isotonic fluids when hypovolemic Complications rapid corrrection of hypernatremia can lead to cerebral edema and herniation
Hypokalemia	Hyperkalemia
Defintion serum potassium of < 3.5 mEq/L Etiology ↑ insulin hyperglycemia this stimulates endogenous insulin secretion from the pancreas in normal conditions β2-adrenergic agonists alkalosis hyposmolality diarrhea Presentation muscle and cardiac dysfunction muscular symptoms abdominal cramping muscle weakness and cramping cardiac symptoms palpitations parasthesias nausea and vomiting Studies electrocardiogram (ECG) findings U waves T wave flattening Treatment address underlying cause potassium repletion remember to not use dextrose-containing fluids as this will stimulate insulin release and shift potassium within the cell this worsens the hypokalemia replace magnesium in magnesium deficiency	Definition serum potassium of > 5-5.5 mEq/L Etiology insulin deficiency β2-adrenergic antagonists acidosis cells attempt to buffer excess hydrogen ions to shift these ions into the cells in exchange for this intracellular uptake of hydrogen, potassium is transferred out the cell this attempts to achieve electroneutrality digitalis secondary to dose-dependent Na+/K+ -ATPase pump inhibition cell lysis (e.g., rhabdomyolysis) exercise hyperosmolarity succinylcholine TMP-SMX ACE inhibitors Presentation muscle and cardiac dysfunction muscular symptoms myalgias muscle paralysis chest pain cardiac symptoms arrhythmias and palpitations nausea and vomiting parasthesias Studies ECG findings peaked T waves and wide QRS Treatment address underlying cause IV calcium gluconate has no effect on potassium levels but stabilizes the myocardium shifting potassium within cells insulin plus glucose β2-adrenergic agonists lowering body potassium sodium polystyrene sulfonate this is a cation exchange resin dialysis used in patients unresponsive to medical therapy
Hypocalcemia	Hypercalemia
Definition serum total calcium < 8.4 mg/dL decreased albumin can cause a decreased total calcium but a normal free calcium (thus the patient is asymptomatic) ionized fraction of calcium < 4.4 mg/dL Etiology renal failure hypoparathyroidism vitamin D deficiency hypomagnesemia inhibits PTH release pancreatitis alkalemia Presentation seizures tetany Chvostek sign ipsilateral facial muscle contraction caused by tapping the facial nerve Trousseau sign carpopedal spasms by inflating the sphygmomanometer above systolic blood pressure Studies QTc prolongation Treatment address underlying cause asymptomatic or patients with chronic hypocalcemia oral calcium replacement therapy such as calcium citrate calcium carbonate vitamin D supplementation thiazides for patients with hypoparathyroidism symptomatic patients IV calcium gluconate first-line chronic renal failure phosphate binders oral calcium replacement calcitriol	Definition serum total calcium > 10.5 mg/dL ionized fraction of calcium > 5.6 mg/dL Etiology hyperparathyroidism humoral hypercalcemia of malignancy secondary to parathyroid hormone-related peptide (PTHrP) associated with squamous cell cancer and solid tumors involving the lung esophageus skin cervix breast kidney vitamin D overdose granulomatous diseases like sarcoidosis thiazide diuretics lithium calcium-containing antacids familial hypocalciuric hypercalcemia immobilization Presentation nephrolithiasis polyuria muscle weakness bone pain abdominal pain secondary to bowel hypomotility and constipation confusion stupor coma mnemonic: stones (renal), bones (pain), groans (abdominal pain), thrones (↑ urinary frequency), and psychiatric overtones (altered mental status) Studies ECG shortened QTc interval Treatment address underlying cause IV isotonic normal saline increases urinary calcium excretion calcitonin impairs bone resorption increases urinary calcium excretion bisphosphonates (e.g., zoledronic acid and pamidronate) has a delayed onset of action impairs bone resorption long term calcium control loops diuretics increases urinary calcium excretion
Hypomagnesemia	Hypermagnesemia
Definition typically serum magnesium < 1.8 mg/dL Etiology magnesium redistribution refeeding syndrome malnutrition alcohol use disorder anorexia nervosa proton pump inhibitors loop diuretics digoxin Presentation tetany torsades de pointes hypokalemia hypocalcemia when significant (< 1.2 mg/dL) Studies ECG U waves T wave flattening QT prolongation widened QRS complexes Treatment magnesium repletion asymptomatic oral magnesium supplementation severe or symptomatic hypomagnesemia IV magnesium sulfate	Definition typically serum magnesium > 2.6 mg/dL Etiology increased magnesium ingestion magnesium cathartics antacids laxatives dietary supplements renal insufficiency Presentation ↓ deep tendon reflexes bradycardia cardiac arrest hypocalcemia Studies ECG PR, QRS, and QT prolongation heart block Treatment address underlying cause IV isotonic saline loop diuretics can be considered
Hypophosphatemia	Hyperphosphatemia
Definition serum phosphate < 2.5 mg/dL Etiology refeeding syndrome hungry bone syndrome inadquate phosphate intake hyperparathyroidism phosphate binders Presentation weakness muscle and bone pain osteomalacia rickets Treatment address underlying cause mild hypophosphatemia increase dietary phosphate intake moderate hypophosphatemia oral phosphate replacement therapy IV phosphate replacement in patients who are on a ventilator severe hypophosphatemia IV phosphate replacement	Definition serum phosphate > 4.5 mg/dL Etiology acute phosphate ingestion hypoparathyroidism vitamin D toxicity renal failure rhabdomyolysis tumor lysis syndrome Presentation typically asymptomatic Treatment address underlying cause dietary modifications phosphate binders calcium carbonate or acetate

Blood, Plasma, Serum	Reference Range
ALT	8-20 U/L
Amylase, serum	25-125 U/L
AST	8-20 U/L
Bilirubin, serum (adult) Total // Direct	0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca²⁺)	8.4-10.2 mg/dL
Cholesterol, serum	Rec: < 200 mg/dL
Cortisol, serum	0800 h: 5-23 μg/dL //1600 h: 3-15 μg/dL 2000 h: ≤ 50% of 0800 h
Creatine kinase, serum	Male: 25-90 U/L Female: 10-70 U/L
Creatinine, serum	0.6-1.2 mg/dL
Electrolytes, serum
Sodium (Na⁺)	136-145 mEq/L
Chloride (Cl^-)	95-105 mEq/L
Potassium (K⁺)	3.5-5.0 mEq/L
Bicarbonate (HCO₃^-)	22-28 mEq/L
Magnesium (Mg²⁺)	1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)
24-28 wks // 32-36 wks	30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks	40-220 ng/mL // 80-350 ng/mL
Ferritin, serum	Male: 15-200 ng/mL Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma	Male: 4-25 mIU/mL Female: premenopause: 4-30 mIU/mL midcycle peak: 10-90 mIU/mL postmenopause: 40-250
pH	7.35-7.45
PCO₂	33-45 mmHg
PO₂	75-105 mmHg
Glucose, serum	Fasting: 70-110 mg/dL 2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation	Fasting: <5 ng/mL Provocative stimuli: > 7ng/mL
Immunoglobulins, serum
IgA	76-390 mg/dL
IgE	0-380 IU/mL
IgG	650-1500 mg/dL
IgM	40-345 mg/dL
Iron	50-170 μg/dL
Lactate dehydrogenase, serum	45-90 U/L
Luteinizing hormone, serum/plasma	Male: 6-23 mIU/mL Female: follicular phase: 5-30 mIU/mL midcycle: 75-150 mIU/mL postmenopause 30-200 mIU/mL
Osmolality, serum	275-295 mOsmol/kd H₂O
Parathyroid hormone, serume, N-terminal	230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C)	20-70 U/L
Phosphorus (inorganic), serum	3.0-4.5 mg/dL
Prolactin, serum (hPRL)	< 20 ng/mL
Proteins, serum

Hematologic	Reference Range
Bleeding time	2-7 minutes
Erythrocyte count	Male: 4.3-5.9 million/mm³ Female: 3.5-5.5 million mm³
Erythrocyte sedimentation rate (Westergren)	Male: 0-15 mm/h Female: 0-20 mm/h
Hematocrit	Male: 41%-53% Female: 36%-46%
Hemoglobin A1c	≤ 6 %
Hemoglobin, blood	Male: 13.5-17.5 g/dL Female: 12.0-16.0 g/dL
Hemoglobin, plasma	1-4 mg/dL
Leukocyte count and differential
Leukocyte count	4,500-11,000/mm³
Segmented neutrophils	54%-62%
Bands	3%-5%
Eosinophils	1%-3%
Basophils	0%-0.75%
Lymphocytes	25%-33%
Monocytes	3%-7%
Mean corpuscular hemoglobin	25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration	31%-36% Hb/cell
Mean corpuscular volume	80-100 μm³
Partial thromboplastin time (activated)	25-40 seconds
Platelet count	150,000-400,000/mm³
Prothrombin time	11-15 seconds
Reticulocyte count	0.5%-1.5% of red cells
Thrombin time	< 2 seconds deviation from control
Volume
Plasma	Male: 25-43 mL/kg Female: 28-45 mL/kg
Red cell	Male: 20-36 mL/kg Female: 19-31 mL/kg

Cerebrospinal Fluid	Reference Range
Cell count	0-5/mm³
Chloride	118-132 mEq/L
Gamma globulin	3%-12% total proteins
Glucose	40-70 mg/dL
Pressure	70-180 mm H₂O
Proteins, total	< 40 mg/dL

Sweat	Reference Range
Chloride	0-35 mmol/L
Urine
Calcium	100-300 mg/24 h
Chloride	Varies with intake
Creatinine clearance	Male: 97-137 mL/min Female: 88-128 mL/min
Estriol, total (in pregnancy)
30 wks	6-18 mg/24 h
35 wks	9-28 mg/24 h
40 wks	13-42 mg/24 h
17-Hydroxycorticosteroids	Male: 3.0-10.0 mg/24 h Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total	Male: 8-20 mg/24 h Female: 6-15 mg/24 h
Osmolality	50-1400 mOsmol/kg H₂O
Oxalate	8-40 μg/mL
Potassium	Varies with diet
Proteins, total	< 150 mg/24 h
Sodium	Varies with diet
Uric acid	Varies with diet
Body Mass Index (BMI)	Adult: 19-25 kg/m²