Because you need electrolytes to live. Every cell in your body uses electrolytes like sodium (Na), Potassium (K), Calcium (Ca), Magnesium (Mg) and other critical ions for cellular functions, proper osmotic gradients, enzymatic activity and even coordination of complex functions like muscle contraction and nerve conduction. All the cells in your body are full of little ion channels that are importing or exporting (or passively diffusing) these ions for physiological functions, and several organ systems (pituitary, adrenals, kidneys) in your body are in charge of maintaining tight control of their concentration in the blood. Very small changes in their concentration – often as little as a doubling or halving of their normal concentrations – can lead to disaster. If, for instance, you became profoundly low in calcium your heart will very quickly fail to beat as muscle requires calcium gradients for contraction.
The measurement of the electrolytes in your blood is a critical component of the evaluation of the health of almost every patient in the hospital. The basic metabolic panel is collected on most inpatients every single day as a critical tool in understanding what’s going on with your patient’s overall health. It provides vital clues into what their kidneys are doing, how their endocrine system is functioning, what disease processes may be at play, and occasionally whether someone is in acute need of rescue. We usually present the data like so:
Na+ | Cl – | BUN
——————————–< Glucose K+ | bicarb | Creatinine 135-145 | 98-106 | 7-18 ------------------------------------< 70-115 3.5 - 5.1 | 22-29 | 0.6-1.2 (BUN = Blood Urea Nitrogen) Seeing this little diagram gives you a great deal of information about what's going on with your patient in a minimum of space. Also of note is what is called the anion gap. The primary cation - Sodium (Na) - and the primary anions (cloride and bicarbonate) don't balance out in terms of charge. Usually if you add the chloride concentration to the bicarb concentration (e.g. 104 + 22 = 126), and then subtract this from the sodium (138 - 126 = 12) you get a value called the "gap" which represents other cations in the blood that are not measured in the basic panel. I realize this seems complicated but it's really not. Basically if it's in the normal range (12 +/-2) it means there likely isn't some hidden anion not being measured and causing trouble - like the ketoacids that run amok in diabetic ketoacidosis. So with that little introduction it's time to go over electrolyte troubles, and because you guys liked the last case presentation so much, I think it’s time for another. This one will be much more challenging. Let’s start with the case, again, based on a true story but jumbled/scrubbed for privacy.
Chief complaint: Shortness of breath (SOB)
History of Present Illness: A 53 year old white male farmer with a 5 year history of chronic obstructive pulmonary disease (COPD) and three year history of type II diabetes presented to his doctors office with SOB of 5 days duration. His primary care doctor had managed several previous episodes of COPD exacerbation with 2-4 week courses of prednisone, and nebulizer treatments (bronchodilators). Concerned that the patient was failing to adequately oxygenate after several such treatments in her office his doctor refers him to the ER for admission to the hospital.
The rest of the case, and more fun with electrolytes below the fold.
Past Medical History: Type II diabetes mellitus x 3 years, COPD x 5 years, Hypertension, and Hyperlipidemia.
Past Surgical History: Appendectomy @ 21 years, vasectomy @ 39 years.
Social History: The patient smoked 2 packs of cigarettes a day for 24 years (48 pack year history) and quit 3 years ago. The patient denies drinking alcohol or using other drugs.
Family History: Parents both had coronary artery disease. A brother has diabetes and had a heart attack at age 55.
Medications: For diabetes Insulin glargine 80U at bedtime (this is a lot), regular insulin with meals, and glyburide. His insulin use has increased exponentially since his diagnosis a few years ago. For Hypertension Valsartan (ACE inhibitor), and lasix (a diuretic). For COPD, acute exacerbations predisone for 2-4 weeks (he started taking a course of prednisone three days ago), for daily management albuterol inhaler, duoneb, and advair.
Review of Systems: Patent complains of no chest pain, palpitations, pain with breathing, cough, loss of consciousness, abdominal pain, fevers, sweats, weight loss, fatigue, constipation, nausea, vomiting, or diarrhea.
Physical Exam: Vitals – Temp 37.3 (afebrile), Pulse 115, Blood pressure 134/88, Respirations 37 (normal 12-20), Oxygen saturation 90% on room air which increased to 96% with 3 liters oxygen by nasal cannula.
General: The patient is a moon-faced, centrally-obese male (294 lbs at 5’9″) appearing older than his stated age, sitting up in the ER bed breathing rapidly using accessory muscles with each inspiration.
Head/Ears/Eyes/Nose/Throat (HEENT): Pupils equal, round, and reactive to light (PERRL), mucous membranes are dry, mouth shows some thrush (white plaque on tongue).
Pulmonary:: Loud expiratory wheezes are heard bilaterally, no dullness to percussion, or egophony heard. The thorax is barrel-shaped with a nuchal fat pad. Patient is using accessory muscles and great effort to breath.
Cardiac: Tachycardia, regular rhythm, heart sounds faint due to body habitus. No murmurs rubs or gallops are appreciated. Point of maximal impulse is positioned normally in the midclavicular line.
Abdomen: Soft, nontender.
Neuro: No focal deficits, no weakness, paralysis, cranial nerves II-XII intact.
Extremities: Good peripheral pulses with normal capillary refill (good perfusion)
Skin: Flushed, no rashes.
At this point you’ve met the patient and results from preliminary labs the ER doc ordered are coming in. The chest X-ray rules out pneumonia or pneumothorax, and the heart is of normal size and position. The ECG shows no rhythm abnormalities or signs suggestive of heart attack. A preliminary troponin level comes back normal (heart attack unlikely). The complete blood count shows a leukocytosis (white blood cells 26 thousand/deciliter – normal < 12 thousand -, hematocrit, hemoglobin and platelets normal). A preliminary differential diagnosis would include COPD exacerbation (much like last time), myocardial infarction/arrhythmia, pulmonary embolism, pleural effusion, pneumothorax, and pneumonia/infection. All but COPD and pulmonary embolism have been largely eliminated by exam and initial tests. Then you see this chemistry panel: 135 | 98 | 24 ------------------< 558 2.5 | 18 | 0.8 And you say, WTF? What initial interventions are required to keep this man alive? What do you think is happening? What would be the very next test you would order (it probably should have been done right off the bat)? What about that metabolic panel is very strange? I'll fill in tests, history and physical findings in comments.