Creatinine, serum concentrations

Direct measurement of creatinine clearance (CrCl) requires collection of urine over an extended time interval (usually 24 hours) with measurement of urine volume, urine creatinine concentration, and serum creatinine concentration (Table 22-1). Because kidney function can fluctuate significantly during ARF, this method may underestimate or overestimate kidney function depending on whether ARF is worsening or resolving. 

Ucr = urine creatinine concentration, mg/dL V = volume of urine, mL Scr = serum creatinine concentration, mg/dL T = time of urine collection, minute (Note time equals 1440 minutes for a 24-hour collection)... 

EssCOrr= corrected steady-state creatinine excretion Scr, = first serum creatinine concentration Scr2 = second serum creatinine concentration E = creatinine excretion... 

A 73-year-old man with a history of diabetes mellitus, chronic kidney disease, gout, osteoarthritis, and hypertension is hospitalized with possible urosepsis. He recently completed a 10-day course of antibiotics and was ready for discharge when his morning labs showed an increase in BUN and serum creatinine concentration. Upon examination, he was found to have 2+ pitting edema, weight gain, nausea, elevated blood pressure, and rales on chest auscultation. 

Elevated serum creatinine concentration (normal range approximately 0.6 to 1.2 mg/dL [53 to 106 pmol/L])... 

Fig. 9 Plot of kanamycin elimination half-life versus serum creatinine concentration in patients with varying degrees of (stable) renal failure.

A study of 398 male and 133 female civil servants in London, England, measured blood pressure, PbB, and serum creatinine concentration the study found no correlation between blood pressure and PbB after adjustment for significant covariates, including sex, age, cigarette smoking, alcohol intake, and body mass index in a stepwise multiple regression analysis (Staessen et al. 1990). 

The GFR decreases in patients receiving ACE inhibitors because of inhibition of angiotensin II vasoconstriction on efferent arterioles. Serum creatinine concentrations often increase, but modest elevations (e.g., absolute increases of less than 1 mg/dL) do not warrant changes. Therapy should be stopped or the dose reduced if larger increases occur. 

The serum creatinine concentration of a human volunteer was found to be 1.2 mg/dL. Over a 24-hour period, 1.6 L of urine was collected and the concentration of creatinine in urine was found to be 98 mg/dL. What is the creatinine clearance of the volunteer ... 

The serum creatinine concentration of a 60 year old male weighing 150 pounds was found to be 1 mg/dL. What is his creatinine clearance ... 

For a 42-year-old female weighing 186 lb, the serum creatinine concentration was found to be 960 mcg/dL. What is her creatinine clearance ... 

Kidney Failure, Acute A clinical syndrome characterized by a sudden decrease in glomerular filtration rate, often to values of less than 1 to 2 ml per minute. It is usually associated with oliguria (urine volumes of less than 400 ml per day) and is always associated with biochemical consequences of the reduction in glomerular filtration rate such as a rise in blood urea nitrogen (BUN) and serum creatinine concentrations. [NIH]... 

Ccr is corrected to 70 kg body weight or 1.73 body surface area. For adults, if only serum creatinine concentrations (Scr) are available, a Ccr (corrected to 70 kg body weic may be estimated in men as (140 - Age)/Scr. For women, multiply this result by 0.85. N( This equation cannot be used for estimating Ccr in infants or children. 

Electrical cardioversion It may be desirable to reduce the dose of digoxin for 1 to 2 days prior to electrical cardioversion of atrial fibrillation to avoid the induction of ventricular arrhythmias, but physicians must consider the consequences of increasing the ventricular response if digoxin is withdrawn. If digitalis toxicity is suspected, delay elective cardioversion. If it is not prudent to delay cardioversion, select the lowest possible energy level to avoid provoking ventricular arrhythmias. Lab test abnormalities Periodically assess serum electrolytes and renal function (serum creatinine concentrations) the frequency of assessments will depend on the clinical setting. 

Renal function Impairment The major toxicity of foscarnet is renal impairment, which occurs to some degree in most patients. Approximately 33% of 189 patients with AIDS and CMV retinitis who received IV foscarnet in clinical studies developed significant impairment of renal function, manifested by a rise in serum creatinine concentration to 2 mg/dL or more. 

Baseline tests CBC, hepatic function, pregnancy test, TSH, renal function, uric acid, HCVRNA level. Exclusions to treatment platelet count <90,000 cells/mm (as low as 75,000 cells/mm in patients with cirrhosis) absolute neutrophil count < 1,500 cells/mm serum creatinine concentration > 1.5 X upperlimit of normal abnormal thyroid function... 

In women, the estimated value is 85% of the calculated value at the same weight and serum creatinine concentration. Although this equation is useful in adjusting for age, weight, and the measured serum creatinine level, it does not account for individual variation. This formula has been validated in ambulatory and hospitalized patients, but some studies suggest that it may not be accurate when... 

Others have stated that metformin is contraindicated when serum creatinine concentrations are over 133 pmol/1 (1.5 mg/dl) in men or 124 pmol/l (1.4 mg/dl) in women (15). 

Reconsideration of contraindications has also been proposed in a prospective study in patients with serum creatinine concentrations of 130-220 pmol/1 and coronary heart disease (n — 226), congestive heart failure (n = 94) and chronic obstructive pulmonary disease (n = 91). Half of the patients continued to take metformin and the other half stopped (39). Bodyweight and HbAic increased over 4 years in those who stopped taking metformin. Lactic acid concentrations were similar in the two groups. Deaths were similar in the two groups (62 and 64 respectively). The incidences of myocardial infarction, all cardiovascular events, and cardiovascular mortality were the same. Changes in additional therapy were only significant for insulin (30% versus 45% respectively) and diet (25% versus 0% respectively). 

A 61-year-old woman developed a bradydysrhythmia after a cardiac arrest (57). Her lactate concentration was 18 mmol/1, pH 6.60, blood glucose 19 mmol/1, and creatinine 1136 pmol/1. She had a 5-year history of type 2 diabetes treated with glimepiride 3 mg/day and metformin 850 mg tds, and 4 months before admission had had a serum creatinine concentration of 1.1 mg/dl. In the few days before admission she had had abdominal pain, nausea, and a speech disorder. She was treated with hemodialysis, and 6 weeks later the creatinine was 0.54 mg/dl. Further information about events leading to the acute renal insufficiency was not given, but a diagnosis of metformin-associated lactic acidosis was made. 

A 64-year-old man who had had type 2 diabetes for 15 years used insulin 35 units/day without problematic hypoglycemia, but within 2 weeks had three episodes. He was found to have developed renal insufficiency secondary to diclofenac and his serum creatinine concentration had increased to 440 pmol/1. 

Fenofibrate was the probable cause of rises in serum creatinine concentrations in six patients in one clinic (32). The authors therefore recommended routine serum creatinine monitoring at baseline and at 1 month after starting fenofibrate. 

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