Contrast agent-induced nephropathy: a simple way to identify patients with preexisting renal insufficiency

Contrast-induced nephropathy in patients with active cancer undergoing contrast-enhanced computed tomography

PURPOSE

This study was performed to measure the incidence and identify potential predictors of contrast-induced nephropathy (CIN) in cancer patients without chronic kidney disease and with normal or near-normal baseline serum creatinine measures who underwent contrast-enhanced computed tomography (CECT). Severity of CIN was reported based on the RIFLE (risk, injury, failure, loss of kidney function, and end-stage renal disease) classification of acute kidney injury.

METHODS

A retrospective analysis was performed on 820 cancer patients who presented at our emergency department from October 2014 to March 2015. CIN was defined as an increase in creatinine concentration of ≥0.5 mg/dL or ≥25 % above baseline that occurred 48 to 72 h after CECT.

RESULTS

The incidence of CIN was 8.0%. Serial CT examination [odds ratio (OR) 4.09; 95% confidence interval (CI) 1.34-12.56], hypotension before the CT scan (OR 3.95; 95% CI 1.77-8.83), liver cirrhosis (OR 2.82; 95% CI 1.06-7.55), BUN/creatinine >20 (OR 2.54; 95% CI 1.44-4.46), and peritoneal carcinomatosis (OR 1.75; 95% CI 1.01-3.00) were independently associated with CIN. Of 66 CIN patients, 44 met any of the severity criteria of the RIFLE classification. Five of these patients died during hospitalization but only one death was related to renal failure.

CONCLUSIONS

Even when the baseline serum creatinine is ≤1.5 mg/dL, a significant portion of cancer patients are still at risk of CIN. Consecutive CECT examinations, hypotension before CT, liver cirrhosis, dehydration, and peritoneal carcinomatosis seem to predispose patients to CIN.

How to reduce nephropathy following contrast-enhanced CT: a lesson in policy implementation

In excess of 50 contrast-enhanced computed tomography (CT) examinations are typically undertaken in our tertiary hospital NHS Trust each weekday, approximately 13,000 each year. In the Department of Radiology alone, we inject more than 1300 l of iodinated contrast medium per annum. There is a real need to devise a policy to anticipate contrast medium-induced nephropathy (CIN) and minimize its effects, without disrupting the high-intensity CT service. Having written a comprehensive yet pragmatic policy to reduce the incidence of this iatrogenic condition, it seemed sensible to share it with the wider radiology community and share the experience and lessons learnt in engaging all the stakeholders, ushering in the change with as little fuss as possible. The ramifications on primary and secondary care had to be anticipated, resource implications managed, and staff trained. This review is therefore presented in four sections: framing the problem, assessing its size and nature; a succeeding section on the available guidelines and their uptake; the policy itself to reduce CIN in CT is presented in the third section; and crucially, a description of the policy introduction process in the last section.

Lithium-induced renal insufficiency: a longitudinal study of creatinine increases in intellectually disabled adults

BACKGROUND

Lithium has been shown to increase serum creatinine levels in a subgroup of patients. However, lithium-induced increases in serum creatinine have not been well studied with regard to timing, trajectory, or predictability.

METHODS

The medical records of 16 intellectually disabled individuals treated with lithium between 1980 and 2010 in whom serum creatinine levels peaked at 1.5 mg/100 mL or higher (ie, who developed renal insufficiency) were reviewed. These individuals were compared with a group of 36 similar lithium-treated individuals in whom serum creatinine did not reach 1.5 mg/100 mL.

RESULTS

The 16 lithium-treated individuals who developed renal insufficiency had a mean peak serum creatinine level of 1.8 ± 0.3 mg/100 mL while on lithium. The mean time from institution of lithium until the 1.5 mg/100 mL serum creatinine level was first reached was 7.9 years. After lithium was discontinued, overall mean serum creatinine levels did not significantly change. Reaching a serum creatinine level of 1.3 or 1.4 mg/100 mL predicted reaching a 1.5 mg/100 mL level or higher. No significant differences in the age lithium was started, baseline serum creatinine levels, years receiving lithium, sex, or race differentiated those who developed renal insufficiency.

CONCLUSIONS

Prescribing lithium led to elevated serum creatinine levels in some individuals. A serum creatinine level of 1.3 and/or 1.4 mg/100 mL predicted renal insufficiency. Clinical implications of this study are that if 1 serum creatinine result reaches 1.3 mg/100 mL or more, intensive monitoring for further increases is indicated.

Lithium effect on renal glomerular function in individuals with intellectual disability

OBJECTIVE

The current study evaluated the effects of chronic administration of lithium on renal functioning in an intellectually disabled population.

METHODS

Fifty-seven lithium-treated individuals were compared with 24 behaviorally symptomatic controls using a retrospective chart review method. Serum creatinine levels and creatinine clearance activities were compared at baseline, at the time of peak creatinine levels, and at the end of the study in 2006.

RESULTS

The mean length of lithium administration was 8.76 years (range, 1-23 years). Chronic lithium administration yielded a significant increase in peak serum creatinine levels and a decrease in the corresponding creatinine clearance activity. Of the subjects, 22.8% had peak creatinine levels of 1.5 mg or higher per 100 mL (a common threshold for renal insufficiency). This contrasted with 0% (none) for the symptomatic control subjects (P = 0.008). In addition, 26.3% of the lithium-treated subjects had creatinine clearance activities less than 55 mL/min and 17.5% had less than 50 mL/min, both indicative of renal insufficiency, versus none of the symptomatic control subjects (P = 0.004 and P = 0.029, respectively). With lithium withdrawal, further deterioration of renal function did not occur in most cases, and many showed improvement, with decreases in serum creatinine levels and increases in creatinine clearance activity.

CONCLUSIONS

Chronic administration of lithium led to clinically significant increases in serum creatinine levels and decreases in creatinine clearance in lithium-treated intellectually disabled individuals.

Discordance between serum creatinine and creatinine clearance for identification of ED patients with abdominal pain at risk for contrast-induced nephropathy

STUDY OBJECTIVE

Despite creatinine clearance (CrCl) being a better estimate of renal function, serum creatinine (Cr) is more commonly used to screen for renal insufficiency in patients scheduled for an enhanced abdominal computed tomography (CT) in an attempt to reduce the likelihood of contrast-induced nephropathy (CIN). Our objective was to determine the incidence of renal insufficiency (a CrCl <60 mL/min) among patients who have serum Cr below 1.5 mg/dL (the most commonly accepted Cr cutoff for the administration of intravenous contrast). This study was conducted in a population of emergency department patients with acute abdominal pain being considered for CT scan.

METHODS

We performed post hoc analysis of a prospective cross-sectional study that enrolled nongravid adults with acute nontraumatic abdominal pain. Patients on dialysis were excluded. The data that we collected included demographics, history, duration/description of pain, patient reported weight, laboratory data, imaging studies, and final diagnosis. Creatinine clearance values (< or >60 mL/min) were compared to Cr values of 1.0, 1.2, 1.5, and 1.8 mg/dL to determine the percentage of patients at risk for nephropathy after contrast injection at each Cr cutoff. Descriptive statistics were used with 95% confidence intervals (CIs).

RESULTS

Seven hundred sixty-five patients were enrolled; 59% (451/765) had an abdominal CT scan. Of 108 patients with CrCl less than 60 mL/min, 59 patients had a Cr less than 1.8 mg/dL (55%; 95% CI, 45%-64%); 43 had a Cr less than 1.5 mg/dL, the most commonly accepted Cr cutoff for contrast administration (40%; 95% CI, 31%-50%); 21 patients had a Cr less than 1.2 mg/dL (19%; 95% CI, 12%-28%); and 10 had a Cr less than 1.0 mg/dL (9%; 95% CI, 5%-16%).

CONCLUSION

The most commonly used Cr cutoff (1.5 mg/dL) for contrast administration fails to identify 40% of the patients at risk for CIN. Future studies should address whether using CrCl rather than serum Cr decreases the incidence of contrast-induced nephropathy.

Occult renal impairment is common in patients with peripheral vascular disease and normal serum creatinine

OBJECTIVE

The incidence of peripheral vascular disease (PVD) and angiography/angioplasty is rising annually. The UK Small Aneurysm Trial and other trials have shown renal function is a predictor of increased mortality and failed infrainguinal bypass despite patent vessels. Renal function is classically assessed by serum creatinine (SCr). However, SCr can be normal despite significant renal impairment. A more sensitive test is creatinine clearance (CrCl) as determined by 24-hour urine collection in combination with SCr. We studied the incidence of renal impairment, as defined by CrCl, in PVD patients with normal SCr.

METHODOLOGY

All patients with PVD sufficient to necessitate angiography and normal SCr (< or =120 micromol/l - men; < or =97 micromol/l - women) had their CrCl assessed prior to angiography: using both 24-hour urine collection and the Cockcroft-Gault formula. Various blood tests, a detailed history and examination were performed. A control group of arthritic patients, age and sex-matched with similar SCr, also had their CrCl determined.

RESULTS

65 of 76 patients (86%) with normal SCr had a subnormal CrCl (<100 ml/min) and 49 (65%) had a CrCl below 60 ml/min. In the control group of arthritic patients, the proportion having impaired CrCl was significantly less - 67% below 100 mls/min (p=0.0471) and only 15% below 60 mls/min (p<0.0001). The median and interquartile range CrCl of 52 [38-81] mls/min for PVD patients was significantly worse than for control patients (80 [68-119] mls/min -p<0.0001). The Cockcroft-Gault formula for calculating CrCl did not correlate well with the urinary CrCl for the control group but did for PVD patients (p<0.0001). Factors associated with a significantly reduced CrCl were age of at least 75 years, SCr of at least 85 micromol/l and a history of coronary heart disease (all p<0.05). This had a sensitivity of 88% and specificity of 82% for identifying subnormal CrCl. Statin use was associated with a significantly improved CrCl (p=0.040).

CONCLUSION

Most PVD patients with normal serum creatinine have occult, significantly impaired renal function as defined by creatinine clearance. Vascular surgeons should include creatinine clearance in pre-operative assessment of renal function especially in patients over 75 years old, with a history of coronary heart disease or a serum creatinine over 85 micromol/l. The method of determining creatinine clearance could be the Cockcroft-Gault calculation or ideally 24-hour urinary creatinine clearance measurement. This would allow appropriate early referral to a nephrologist for further investigation and management. It is worth noting that statin use seems to be associated with a protective effect on renal function.