A 51-year-old lady presented to our emergency department because of generalized body ache and marked weakness in both lower extremities for two days duration. She had no history of vomiting, diarrhea, frequent urination, recent use of laxatives or diuretics, current or previous use of lithium, licorice ingestion, or activities leading to profuse sweating. Past medical history was significant for type 2 diabetes mellitus, hypertension, seizure disorder and schizoaffective disorder. She also had a long-term history of alcoholism, consuming two to three pints of vodka every day for about 20 years. Her last drink of alcohol was about 48 hours prior to presentation. On examination, her weight was 79 kg, height 65 inches, body mass index 29.3 kg/m2. Vital signs were stable, temp 98.6°F, heart rate 68 bpm, respiratory rate 18, blood pressure 113/71 mmHg and oxygen saturation 98% on room air. She was alert and oriented, there was no thyromegaly or lymphadenopathy. Cardiac examination revealed a regular sinus rhythm with no murmurs. There were no deformities or edema of the extremities and distal pulses were present. There was no cushingoid facies, buffalo hump or abdominal striae noted. Neurological examination revealed bilateral lower limb weakness of 4/5, with intact sensory system and reflexes. Cranial nerve examination was unremarkable.
Biochemical analysis of the serum showed severe electrolyte disturbances, a potassium level of 2.3 mmol/L (reference 3.6−5.1 mmol/L), magnesium level of 0.9 mg/dL (reference 1.8−3.0 mg/dL), phosphorus level of 2.0 mg/dL (reference 2.4−4.6 mg/dL), corrected calcium level of 7.8 mg/dL (reference 8.9−10.3 mg/dL). Renal function was mildly deranged with Creatinine of 1.35 mg/dL (reference 0.4−1.3 mg/dL) and BUN of 12 mg/dL (reference 8−20mg/dL). The results of hepatic enzymes, AST 113 IU/l (reference 15−41 IU/l), ALT 42 IU/l (reference 17−63 IU/l) was suggestive of alcohol induced hepatic damage. Electrocardiogram (ECG) () showed no arrhythmias, but changes characteristic of hypokalemia with increased amplitude of the U-wave and marked corrected QT segment prolongation (QTc 551 ms). Patient was admitted to intensive care unit for severe hypokalemia management and cardiac monitoring. Aggressive supplementation of electrolytes was initiated (), however despite supplementation with enteral and parenteral potassium as well as magnesium and phosphate, potassium level failed to increase () and subsequently she had a sinus bradycardia followed by asystole. Cardiopulmonary resuscitation was initiated when asystole was noted, return of spontaneous circulation was obtained after 8 minutes of resuscitation. Patient was mechanically ventilated for two days and her own efficient respiration was reestablished, then she was successfully extubated. During the following days, the patient was conscious, alert and oriented to time, place and person. Further laboratory testing revealed thyroid- stimulating hormone level was 1.100 mIU/L (reference 0.45−4.50 mIU/L). Active renin level was 0.653ng/ml/hr (reference 0.167−5.38 ng/ml/hr), aldosterone levels was <0.01 ng/dL (reference 0.00− 30 ng/dL). Creatine kinase (CK) level was 6922 U/L (reference 38–297 IU/L), indicating rhabdomyolysis. The arterial blood gas analysis revealed pH of 7.430, partial pressure of carbon dioxide was 29 mmHg; partial pressure of oxygen was 74 mmHg; HCO3 was 25 mmol/L and base excess of -4.7 mmol/L. Urinalysis showed dilute urine of 1.010 g/mL specific gravity (reference 1.005 to 1.030), Urine pH of 6.5, and no proteinuria. Urine electrolytes were measured on spot urine analysis and twenty-four-hour urine collection, result depicted in . Serial electrocardiogram monitoring showed resolution of ECG changes (). Follow up laboratory tests revealed normalization of electrolytes level (). Post cardiac arrest serial ECGs didn’t reveal any ischemic changes, cardiac enzymes were not elevated and echocardiogram revealed normal left ventricular systolic function, Ejection Fraction of 60–65%. Cardiac arrest was presumed to be secondary to severe hypokalemia and there was no necessity for further cardiac evaluation. She was then discharged from the hospital with recommendations for abstinence from alcohol. Follow up outpatient appointment with primary care physician was provided.
The formula for computing Cockcroft-Gault is given by CrCl = ((140 - age) * adjusted weight * (gender_coefficient)) / (serum creatinine * 72), where the gender_coefficient is 1 if male, and 0.85 if female. The serum creatinine concentration is in mg/dL.
The patient's gender is female, which means that the gender coefficient is 0.85.
The patient is 51 years old. 
The concentration of creatinine is 1.35 mg/dL. 
The formula for computing the patient's BMI is (weight)/(height * height), where weight is the patient's weight in kg and height is the patient's height in m.
The patient's height is 65.0 in, which is 65.0 in * 0.0254 m / in = 1.651 m. The patient's weight is 79.0 kg. The patient's bmi is therefore 79.0 kg / (1.651 m * 1.651 m) = 28.982 kg/m^2.The patient's BMI is 29.0, indicating they are overweight/obese.
Because the patient is overweight/obese, we use the adjusted body weight formula to get the adjusted weight used for Cockroft-Gault Equation. Shown below is the computation for IBW (ideal body weight).
The patient's gender is Female.
The patient's height is 65.0 in. 
For females, the ideal body weight (IBW) is calculated as follows:
IBW = 45.5 kg + 2.3 kg * (height (in inches) - 60)
Plugging in the values gives us 45.5 kg + 2.3 kg * (65.0 (in inches) - 60) = 57.0 kg.
Hence, the patient's IBW is 57.0 kg.Shown below is the computation for ABW (adjusted body weight).
To compute the ABW value, apply the following formula: ABW = IBW + 0.4 * (weight (in kg) - IBW (in kg)). ABW = 57.0 kg + 0.4 * (79.0 kg  - 57.0 kg) = 65.8 kg. The patient's adjusted body weight is 65.8 kg.

Using the Cockcroft-Gault equation:
CrCl = ((140 - age) * adjusted weight * gender_coefficient) / (serum creatinine * 72).
Plugging the patient's values gives us ((140 - 51) * 65.8 * 0.85) / (1.35 * 72) = 51.212 mL/min. Hence, the patient's creatinine clearance is 51.212 mL/min.