Angela Heithaus, Md, Ps Internal Medicine Seattle Healing Arts Center

The Diagnosis of and Therapy for Common Fluid and Electrolyte Imbalances

Angela Heithaus, MD, PS Internal Medicine Seattle Healing Arts Center

Leonardo da Vinci 

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24 YO M comes to see you complaining that after 2 days of vomiting and diarrhea without fever or abdominal pain or hematochezia that he becomes light headed when standing and thought at one point he was going to pass out. On exam there is no abdominal tenderness

Questions 

What should you document/check?

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How should you treat?

Volume Depletion

Volume Depletion  

Loss of isotonic fluid from the extracellular fluid at a rate exceeding net intake. Can occur through: gastrointestinal tract (vomiting, diarrhea, bleeding)  skin (sweat, burns)  lungs (bronchorrhea, pleural effusion, evaporation)  urine (diuretics, osmotic diuresis, salt wasting nephropathies, and hypoaldosteronism)  acute sequestration in the body in a "third space" that is not in equilibrium with the extracellular fluid (GI obstruction, crush injury, bleeding, acute pancreatitis) 

History and Symptoms of Volume Depletion History vomiting, diarrhea, diuretic use, or polyuria (may identify the source of fluid loss)

Symptoms lethargy, easy fatiguability, thirst, muscle cramps, and postural dizziness (volume depletion)  Generalized weakness, irritability, maybe twitching, seizures (if also severely hyponatremic)  muscle weakness, polyuria, polydipsia, confusion 

(from concomitant electrolyte and acid-base disorders)

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PEx findings in Hypovolemia BP, HR, and JVD 

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Skin 

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BP drops in upright position  ‘orthostatic hypotension’ – after two to five minutes of quiet standing, one or more of the following is present:  At least a 20 mmHg fall in systolic pressure  At least a 10 mmHg fall in diastolic pressure  Symptoms of cerebral hypoperfusion (dizziness)  HR increase by more than 10-20 bpm Decreased JVD Increased pigmentation, decreased turgor, dry axilla

Mucous membranes 

Tongue and oral mucosa dry

Laboratory Studies 

Urine      

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urinalysis can be normal sodium concentration < 25 meq/L and may be as low as 1 meq/L chloride concentration low osmolality >450 mosmol/kg specific gravity > 1.015 oliguria

Blood    

Elevated serum sodium = dehydration If [Na] WNL then pt not dehyrated but hypovolemic Elevated BUN/plasma creatinine level HCT (relative polycythemia) and plasma albumin level increases

Replacement Therapy 

IVF Bolus 5cc/kg over 20 minutes  Usually rounded to 500cc for adults and extended to 30 minutes  Normal Saline (isotonic) best  Ringers lactate (has bicarb) if >4 liters will be given 

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This prevents development of metabolic acidosis

IV Catheters 

18 gauge best

Replacement Therapy Precautions 

Excess NS can cause pulmonary edema in some pts: Elderly pts with hx of CHF  Pts with known severe VHD  Renal failure pts 

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In these pts use 3cc/kg over 30 minutes for boluses and listen to lungs often, measure SaO2 if possible

Answers 

What should you document? 

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How much volume should you replete and how fast? 

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Orthostatic BP/HR- (pt still hypovolemic?)

Bolus 500cc over 30 minutes

Which type of fluid should you use? Normal Saline (isotonic) best  Ringers lactate (has bicarb) if >4 liters anticipated 

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This prevents development of metabolic acidosis

Leonardo continued… 

When have you given enough IVF? 

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Recheck orthostatic pressures and sx

If still orthostatic? 

Rebolus, repeat cycle until asymptomatic, making urine, mucous membranes moist

Sophia Loren 

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70 YO F with H/O HTN on HCTZ presents C/O nausea and malaise x 1 month PEx is WNL Labs: Na+ 121

Clinical Manifestations of Hyponatremia Plasma Na+ 125-130 meq/L nausea and malaise Plasma Na+ <115-120 meq/L headache, lethargy, and obtundation and eventually seizures, coma and respiratory arrest

Differential Diagnosis for Hyponatremia 

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In almost all cases, results from the intake (either oral or intravenous) and subsequent retention of water In almost all cases, occurs because there is an impairment in renal water excretion, due most often to an inability to suppress ADH release

ADH 

Elevated 

Effective circulating volume depletion 

Heart failure, cirrhosis, thiazide diurectics

Syndrome of Inappropriate ADH secretion  Hormonal changes 

Adrenal insufficiency, hypothyroidism, pregnancy

Evaluation of Patients with Hyponatremia 

Assess volume status of patient Hypovolemia: orthostatic, dry mucous membranes  Hypervolemia: peripheral edema, pulmonary edema, JVD, ascites 

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For Euvolemic pt: Check TSH  Check urine osmolarity for SIADH (inappropriately concentrated urine- should be dilute in this setting) 

Treatment of Hyponatremia 

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Initial treatment in such patients typically consists of gradual correction of the hyponatremia via water restriction or the administration of isotonic saline (or oral salt) More aggressive therapy is indicated in patients who have symptomatic or severe hyponatremia (plasma sodium concentration below 110 to 115 meq/L).

Gabriele Falloppio 

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60 yo male with diarrhea x 1 wk, no vomiting; good PO intake, comes to see you because of mild intermittent leg cramps PEx is unremarkable, there is no abdominal tenderness or neurological deficit Labs reveal K of 2.9, otherwise WNL

Hypokalemia  

GI, urinary losses Mild loss, K+ between 3.0 and 3.5 meq/L   

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usually produces no symptoms replace lost K+ and treat underlying disorder (such as vomiting, diarrhea) treatment is usually started with 10 to 20 meq of potassium chloride given two to four times per day (20 to 80 meq per day), depending on the severity of hypokalemia and on whether hypokalemia developed acutely or is chronic sequential monitoring of plasma K+ is essential to determine continued requirements, with frequency of monitoring dependent on the severity of hypokalemia

Severe Hypokalemia 

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Symptoms generally do not become manifest until the serum K+ is below 3.0 meq/L Muscular abnormalities 

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Cardiac arrhythmias and ECG abnormalities 

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muscle cramps, rhabdomyolysis, and myoglobinuria PAC, PAT, PVC, AVB, VT

Renal abnormalities 

impaired urinary concentrating ability (which may be symptomatic with nocturia, polyuria and polydipsia

Enrico Fermi 

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60 YO M comes in for physical exam which is WNL; labs reveal Ca 12.6 Is further evaluation indicated and if so, what?

Calcium  

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Range 8.5-10.6 mg/dL Plasma Ca2+ concentration includes all the Ca2+ in the plasma, of which only about 45 percent circulates in the physiologically important ionized or unbound state. Common exception occurs in patients with hypoalbuminemia in whom the concomitant decrease in ion binding leads to a reduction in the total plasma Ca2+ concentration without change in the ionized form 

if albumin <2.0 g/dL (roughly 2.0 g/L less than normal), then the corrected plasma Ca2+ concentration would be 7.5 + (2 x 0.8) or 9.1 mg/dL, which is normal

Differential Diagnosis of Hypercalcemia 

Hyperparathyroidism  

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Cancer  

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>90% of ambulatory cases Primary hyperparathyroidism is most often due to a parathyroid adenoma solid tumors and leukemias Local resorption of bone induced by metastases (mediated by local release of cytokines such as tumor necrosis factor and interleukin-1) or the production of humoral osteoclast activators, particularly PTH-related protein

Hyperthyroidism 

15-20% of patients can develop mild hypercalcemia

Evaluation of Hypercalcemia 

Correct diagnosis in 95% of cases by evaluating:    

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History PEx CXR (r/o malignancy or sarcoidosis) and Lab data: PTH (serum intact), PTHRP related peptide, serum protein electrophoresis (r/o multiple myeloma), creatinine

Primary hyperparathyroidism is often associated with borderline or mild hypercalcemia with the serum calcium concentration often being below 11 mg/dL (2.75 mmol/L)

Treatment Goals in Hypercalcemia 

Lowering serum Ca++ level Saline administration to produce volume expansion and increase urinary Ca++ excretion (oral hydration + high salt diet)  Concurrent tx with biphosphonates) +/calcitonin (decrease bone resorption)  Oral phosphate 250-500 mg QID (decrease absorption in gut) 

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Correcting or decreasing underlying disease 

Hyperparathyroidism