Creatinine concentrations

O Equations to estimate creatinine clearance that incorporate a single creatinine concentration (e.g., Cockcroft-Gault) may underestimate or overestimate kidney function depending on whether acute renal failure 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... 

Several equations have been developed to assess unstable kidney function. The Jelliffe equation (Table 22-1) estimates creatinine clearance by considering the change in serum creatinine over a specified time period.11 While it is more mathematically difficult to calculate, it better estimates creatinine clearance in patients with rapidly changing kidney function compared to an equation that only includes a single creatinine concentration. 

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])... 

The oncologist prescribes the normal doses of idarubicin 12 mg/m2 IV daily for 3 days and cytarabine 100 mg/m2 per day by continuous infusion for 7 days to treat her acute myelogenous leukemia. Her baseline laboratory measurements are significant for an elevated WBC count, a creatinine concentration of 2.5 mg/dL (221 pmol/L), and a bilirubin level of 1.6 mg/dL (27 pmol/L). 

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

Under field exposure conditions, it is recommended to measure PA herbicides in 24-hr urine samples collected starting at the end of the work-shift. Spot samples collected at the end of exposure or the following morning can be used when a 24-hr urine collection is impractical. In this case, the concentration of the compounds should be normalized to creatinine concentration or adjusted for specific gravity. 

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. 

Urinary protein output was assessed by measuring total protein and creatinine concentration for six male and six female captive-bred P roborovskii hamsters. 

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 ... 

Write down the information provided and use the appropriate formula. Creatinine concentration in urine (Cu) = 98 mg/dL... 

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. 

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