Creatinin clearance

Carboplatin displays less nephro-, oto- and neurotoxicity. However, myelosuppression is more frequent, and as the drug is exclusively cleared through the kidney, adjustment of dose for creatinine clearance must be accomplished. 

Before administering this drug to an elderly patient or one that has renal impairment, the primary health care provider may order a creatinine clearance. The initial dose is 50 to 100 mg PO or IV, depending on the results of the creatinine clearance. The nurse reports the laboratory results to the primary health care provider because dosage adjustments may be made on the results of the creatinine clearance. 

The patient s renal function, evaluated on creatinine clearance ... 

Older adults are at increased risk for adverse reactions from the antineoplastic drugs because of the increased incidence of chronic disease, particularly renal impairment or cardiovascular disease. When renal impairment is present, a lower dosage of the antineoplastic may be indicated. Creatinine clearance isused to monitor renal function in the older adult. Blood creatinine levels are likely to be inaccurate because of a decreased muscle mass in the older adult. 

The study of the mechanism of urinary excretion of amylase and the amylase clearance has been the subject of many studies in recent years. Levitt et. al (79) studied the renal clearance of amylase in renal insufficiency, acute pancreatitis and macro-amylasemia. In acute pancreatitis, the kidney cleared amylase at a markedly increased rate. The ratio of the amylase clearance rate to the creatinine clearance rate (Cgm/Ccr) averaged 3 times normal early in the course of acute pancreatitis, and this elevation could persist after the serum amylase returned to normal. Comparison of an lase clearance to creatinine clearance was to minimize irrelevant changes due to variation in renal function. The increased clearance of amylase makes the urinary amylase a more sensitive indicator of pancreatitis. 

Enhancement of the amylase creatinine clearance ratio in disorders other than acute pancreatitis. New Eng. J. Med. (1975), 329-332. 

CBP Cromolyn-binding protein CCK Cholecystokinin CCR Creatinine clearance rate CD Cluster of differentiation (a system of nomenclature for sur ce molecules on cells of the immune system) cluster determinant CDl Cluster of differentiation 1 also known as MHC class I-like surfitce glycoprotein... 

Low molecular weight heparins (adjust dose for renal dysfunction [i.e., creatinine clearance <30 mL/min])... 

Contraindications include serum potassium >5.5 mEq/L at initiation or a creatinine clearance <30 mL/min. 

An aminoglycoside (consider high-concentration [once-a-day] dosing in patients with a creatinine clearance above 30 mL/min) or... 

Ciprofloxacin (400 mg IV q8h and adjust for creatinine clearance) or levofloxacin (750 mg IV qd and adjust for creatinine clearance)... 

Equation to adjust measured phenytoin levels in the setting of creatinine clearance <10 mL/min +/- hypoalbuminemia... 

Creatinine clearance < 60 mL/min/1.73 m2 (stages III-V chronic kidney disease), diabetes mellitus (with renal insufficiency), hypertension, chronic heart failure, cirrhosis, nephrosis, age >75 yr, cholesterol emboli syndrome, multiple myeloma (questionable)... 

Avoid or use cautiously if patient s estimated creatinine clearance is <20 mL/min... 

Two types of diuretics are used for volume management in HF thiazides and loop diuretics. Thiazide diuretics such as hydrochlorothiazide, chlorthalidone, and metolazone block sodium and chloride reabsorption in the distal convoluted tubule. Thiazides are weaker than loop diuretics in terms of effecting an increase in urine output and therefore are not utilized frequently as monotherapy in HF. They are optimally suited for patients with hypertension who have mild congestion. Additionally, the action of thiazides is limited in patients with renal insufficiency (creatinine clearance less than 30 mL/minute) due to reduced secretion into their site of action. An exception is metolazone, which retains its potent action in patients with renal dysfunction. Metolazone is often used in combination with loop diuretics when patients exhibit diuretic resistance, defined as edema unresponsive to loop diuretics alone. 

The major risk related to aldosterone antagonists is hyperkalemia. Therefore, the decision for use of these agents should balance the benefit of decreasing death and hospitalization from HF and the potential risks of life-threatening hyperkalemia. Before and within one week of initiating therapy, two parameters must be assessed serum potassium and creatinine clearance (or serum creatinine). Aldosterone antagonists should not be initiated in patients with potassium concentrations greater than... 

In patients without contraindications, spironolactone is initiated at a dose of 12.5 to 25 mg daily, or occasionally on alternate days for patients with baseline renal insufficiency. Eplerenone is used at a dose of 25 mg daily, with the option to titrate up to 50 mg daily. Doses should be halved or switched to alternate-day dosing if creatinine clearance falls below 50 mL/minute. Potassium supplementation is often decreased or stopped after aldosterone antagonists are initiated, and patients should be counseled to avoid high-potassium foods. At anytime after initiation of therapy, if potassium concentrations exceed... 

Monitor for adequate perfusion of vital organs through assessment of mental status, creatinine clearance, liver function tests, and a stable HR between 50 and 100 beats per minute. Additionally, adequate skin and muscle blood perfusion and normal pH is desirable. 

Severe renal insufficiency (creatinine clearance less than 30 mL/minute)... 

Prior to initiating treatment with a LMWH, baseline laboratory tests should include PT (prothrombin time)/INR, aPTT, complete blood cell count (CBC), and serum creatinine. Monitor the CBC every 3 to 4 days during the first 2 weeks of therapy, and every 2 to 4 weeks with extended use.5 Use LMWHs cautiously in patients with renal impairment. Specific dosing recommendations for patients with a creatinine clearance (CrCl) less than 30 mL/minute are currently available for enoxaparin but lacking for other agents of the class (Table 7-3). Current guidelines recommend the use of UFH over LMWH in patients with severe renal dysfunction (CrCl less than 30 mL/minute).8... 

Obtain a baseline serum creatinine measurement. Calculate the estimated creatinine clearance and adjust the dose of H2RAs and sucralfate according to package insert recommendations. 

Saline laxatives containing magnesium, potassium, or phosphates should be used cautiously in persons with reduced kidney function. Monitor appropriate serum electrolyte concentrations in patients with unstable renal function evidenced by changing serum creatinine or creatinine clearance. 

The dose of lamivudine is 100 mg orally once daily for treatment of chronic hepatitis B. The dose must be adjusted in patients with renal dysfunction [creatinine clearance (CrCl) less than 50 mL/minute]. 

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. 

TABLE 22-1. Equations for Estimation of Creatinine Clearance (CrCI)... 

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. 

FIGURE 22-1. Algorithm for treatment of extracellular fluid expansion. CiCl, creatinine clearance ECF, extracellular fluid HCTZ, hydrochlorothiazide IV, intravenous PO, oral. 

---