MEDizzy - An 83-year-old woman presents for a follow-up of

Feed Library Learning Discuss Leaderboard Journal

Nephrology

An 83-year-old woman presents for a follow-up of hypertension, type 2 diabetes mellitus, and depression. She complains of fatigue and mild dependent edema. Her medications include hydrochlorothiazide 25 mg/d, atenolol 50 mg/d, glyburide 5 mg bid., and paroxetine 20 mg/d. Physical examination shows BP 152/88, weight 42 kg, clear lung fields, normal liver and spleen, and 1+ peripheral edema. She appears mildly pale. CBC shows Hb 9.6 with an MCV of 87 and normal WBC and platelets. Chem profile shows Na 136, K 4.9, CO2 18, Cl 108, creat 1.5, and glucose 178 mg/dL. Liver enzymes are normal. What is the most likely cause of her anemia?

ExplanationAlthough this woman’s serum creatinine level is at the upper end of the traditional “normal” level, her GFR is only 19 mL/min, consistent with Stage 4 chronic kidney disease. The serum creatinine is an imprecise indicator of GFR, particularly when the muscle mass is diminished, as in this thin elderly woman. The most accurate way to determine GFR is by an estimation formula, either the Cockroft-Gault equation or the MDRD formula. The Cockroft-Gault formula is easy to remember: (140−age)(lean weight in kilograms)/(serum creatinine)(72). The value is multiplied by 0.85 in women since a smaller percentage of a woman’s body mass is made up of muscle. A Mild hyperchloremic acidosis, indicated by the low serum bicarbonate, and edema are commonly seen in Stage 4 CKD. (ie, GFR between 15 and 30 mL/min). Anemia caused by erythropoietin underproduction usually occurs with this degree of kidney dysfunction. The anemia of CKD is normocytic. Folic-acid deficiency causes a macrocytic anemia, and iron deficiency result- ing from colon cancer would typically cause a microcytic anemia. Diabetes is not an inflammatory or neoplastic disease and does not cause the anemia of chronic disease. Bone marrow suppression usually causes a decrease in all cellular elements on the CBC (ie, leukocytes and platelets in addition to erythrocytes).