The Epidemic of Chronic Kidney Disease in Patients Referred to a Hematologist for Anemia.
Authors: Zimmer Brian , Wentzel Dana , Reed James , Eid Sherrine , Friedman Eliot , Ahmed Basil , Kopyt Nelson 
Published: October 2019

Abstract
NHANES survey estimates the prevalence of CKD to be approximately 11% in the general population and 25% in the population over 65 years of age, and the prevalence of Chronic Kidney Disease (CKD) associated anemia approaches 75% in Stage 5 CKD. Despite the high prevalence of CKD, and its strong association with anemia, many patients diagnosed with anemia and referred to a hematologist for evaluation frequently have the diagnosis of CKD overlooked, especially if one is using a serum creatinine to assess renal function. A more accurate method of assessing renal function and to appropriately stage CKD is the use of an estimated glomerular filtration rate (eGFR) utilizing the modified MDRD equation. With the realization that CKD clearly has become known as a significant magnifier of cardiovascular risk (CVR), the importance of making the diagnosis of CKD has become quite apparent. Hypothesis: Patients referred to a hematologist for evaluation of anemia represent a population enriched with CKD. A retrospective chart audit was performed on patients being referred to a hematology practice from community physicians for the evaluation of anemia from January 2004 through December 31, 2005. All patients with a prior knowledge of CKD and a history of malignancy or myelodysplastic process were excluded from the study. The cohort consisted of 256 patients (37.5 % male and 62.5 % female) with a mean age of 67.56 ± 15.9 years. The mean serum creatinine was 1.16 ± .74 mg/dL with a mean calculated GFR by the modified MDRD (4 variable) equation of 69.9 ± 34.2 ml/min/1.73 m2.
The mean ± SEM serum creatinine by stage of CKD in our patient population is: Stage 1: 0.67 ± 0.14 mg/dL, Stage 2: 0.92 ± 0.15 mg/dL, Stage 3: 1.40 ± 0.29 mg/dL, Stage 4: 2.23 ± 0.53 mg/dL, and Stage 5: 5.2 ± 2.89 mg/dL. Conservatively, we defined CKD as GFR <60 as urinalysis, imaging, or biopsy data were not available. In conclusion, an astounding 42.2 % of patients referred to a hematologist for the evaluation of anemia have CKD as compared to an estimated prevalence of 11 % in the general population reported by K/DOQI. Not only were these patients not aware of their diagnosis of CKD, but, of note also is the fact that 5.1 % were not aware of the presence of advanced CKD (GFR < 30) and 4 patients had Stage 5 CKD without awareness. 55.8 % of the patients over the age of 65 with anemia have CKD as compared to an estimated 25 % of the general population over the age of 65. This information stresses the need to assess all anemia patients for CKD and to appropriately stage them. Given the well accepted association between CKD and CVR, physicians caring for these patients can then stress the need for aggressive pursuit of both traditional and non traditional risk factor reduction to circumvent the significant CVR that is present in this population.
Prevalence of Abnormal Renal Function by GFR Frequency Percent *K/DOQI = National Kidney Foundation’s Kidney Disease Outcome Quality Initiative GFR > 90 (Normal /K/DOQI* Stage 1) 51 19.9 GFR 89 - 60 (K/DOQI Stage 2) 97 37.9 GFR 59 - 30 (K/DOQI Stage 3) 95 37.1 GFR 29 - 15 (K/DOQI Stage 4) 9 3.5 GFR < 15 (K/DOQI Stage 5) 4 1.6