What is the interpretation and recommended management of the laboratory abnormalities (mild hyperglycemia, low bicarbonate, leukocytosis with neutrophilia, mild normocytic anemia, eGFR 61 mL/min/1.73 m²) in an 81‑year‑old patient?

Laboratory Interpretation and Management in an 81-Year-Old Patient

This patient has mild, clinically insignificant laboratory abnormalities that require targeted evaluation for underlying causes but do not necessitate urgent intervention. The key findings—mild hyperglycemia (115 mg/dL), low bicarbonate (18 mmol/L), leukocytosis with neutrophilia (WBC 12.3, neutrophils 8.9), and Stage 3a CKD (eGFR 61)—warrant systematic assessment but represent common age-related changes in an octogenarian.

Mild Hyperglycemia (Glucose 115 mg/dL)

The fasting glucose of 115 mg/dL indicates impaired fasting glucose or possible diabetes, requiring HbA1c measurement to determine chronicity and guide management. 1

• Obtain HbA1c to determine if this represents chronic hyperglycemia (HbA1c ≥6.5% confirms diabetes) or an isolated finding. 1
• In elderly patients aged 81, hyperglycemia often presents without classic symptoms (polyuria, polydipsia) due to increased renal threshold for glycosuria and impaired thirst mechanisms. 2
• Assess for precipitating factors: recent steroid use, acute illness (infection, cardiovascular event), or medication changes that could cause transient hyperglycemia. 1
• If diabetes is confirmed, avoid aggressive glycemic targets in this age group—hypoglycemia in elderly patients is associated with twofold increased mortality during hospitalization and at 3-month follow-up. 2, 3
• The low bicarbonate (18 mmol/L) makes diabetic ketoacidosis unlikely but warrants checking capillary ketones if glucose remains elevated. 1

Low Bicarbonate (CO2 18 mmol/L)

The low bicarbonate suggests either metabolic acidosis or chronic respiratory alkalosis with metabolic compensation, requiring anion gap calculation and clinical correlation.

• Calculate anion gap: [Na - (Cl + HCO3)] = 135 - (102 + 18) = 15 mEq/L (normal 8-12), indicating a mild high anion gap metabolic acidosis. [@general medicine knowledge@]
• With eGFR 61 mL/min/1.73 m², this likely represents early uremic acidosis from Stage 3a CKD, as renal acid excretion becomes impaired when GFR falls below 60. 2
• Assess for other causes of high anion gap acidosis: lactic acidosis (sepsis, tissue hypoperfusion), ketoacidosis (check ketones if diabetic), or toxic ingestions. [@general medicine knowledge@]
• If chronic kidney disease is the cause, consider oral sodium bicarbonate supplementation if bicarbonate remains <22 mmol/L on repeat testing, as chronic acidosis accelerates CKD progression. [@general medicine knowledge@]

Leukocytosis with Neutrophilia (WBC 12.3, Neutrophils 8.9)

The mild leukocytosis with neutrophilia suggests an inflammatory or infectious process requiring clinical correlation with symptoms, vital signs, and potential sources of infection.

• Evaluate for infection: pneumonia, urinary tract infection, cellulitis, or intra-abdominal pathology, as respiratory and genitourinary infections are leading causes of hospitalization in elderly diabetic patients. 2
• Check vital signs for fever, tachycardia, or hypotension to assess severity and need for urgent intervention. [@general medicine knowledge@]
• Review recent medication history for corticosteroids, which commonly cause leukocytosis with neutrophilia without infection. [@general medicine knowledge@]
• If no clear infectious source is identified, consider stress response from acute illness, pain, or physiologic stress, which can elevate WBC in elderly patients. [@general medicine knowledge@]
• Repeat CBC in 24-48 hours if no intervention is needed, as transient leukocytosis is common and often resolves spontaneously. [@general medicine knowledge@]

Stage 3a Chronic Kidney Disease (eGFR 61 mL/min/1.73 m²)

The eGFR of 61 mL/min/1.73 m² represents Stage 3a CKD, which is common in octogenarians and requires medication adjustment, particularly for diabetes management if diagnosed.

• If metformin is being considered for diabetes management, use with caution at this eGFR level—the American Geriatrics Society recommends checking renal function more frequently and using lower dosages when eGFR is 30-60 mL/min/1.73 m². 2
• Do not initiate metformin if eGFR falls below 45 mL/min/1.73 m² due to increased risk of lactic acidosis. 4
• Monitor eGFR and urine albumin-to-creatinine ratio (UACR) at least annually to assess CKD progression, with more frequent monitoring if declining. 4
• Avoid high-protein diets (>1.0 g/kg/day), as higher protein intake accelerates loss of kidney function in patients with diabetes and mild kidney insufficiency (eGFR 55-60 mL/min/1.73 m²). 2
• Optimize blood pressure control targeting <130/80 mmHg with ACE inhibitor or ARB therapy if proteinuria is present. 4

Mild Normocytic Anemia (Hemoglobin 11.3 g/dL)

The hemoglobin of 11.3 g/dL represents mild normocytic anemia (MCV 88 fL), likely multifactorial from chronic kidney disease, chronic disease, and possible iron deficiency, requiring iron studies and evaluation for blood loss.

• Obtain iron studies (serum iron, TIBC, ferritin, transferrin saturation) to assess for iron deficiency, as 82.7% of patients with CKD and normocytic anemia have low ferritin (<100 μg/mL). 5
• Check reticulocyte count to assess bone marrow response—a low corrected reticulocyte index suggests inadequate erythropoiesis from CKD or chronic disease. 6, 7
• Evaluate for occult gastrointestinal bleeding, particularly given the patient's age and potential use of antiplatelet agents or NSAIDs, which are prescribed in 61-73% of elderly patients with CKD and anemia. 5
• Normocytic anemia regularly develops when GFR drops below 20-30 mL/min, but can occur earlier due to relative erythropoietin deficiency, shortened red cell lifespan, and blood loss. 8
• Avoid erythropoiesis-stimulating agents until hemoglobin falls below 10 g/dL in asymptomatic patients, as these agents should be individualized in CKD-related anemia. 6
• If ferritin is <100 μg/mL, prescribe oral iron supplementation (e.g., ferrous sulfate 325 mg daily), though 56.3% of patients with CKD and anemia already prescribed oral iron have not achieved correction. 5

Low MCHC (31.0 g/dL)

The slightly low MCHC (31.0 g/dL, normal 31.5-35.7) is minimally decreased and likely represents laboratory variation or early iron deficiency, requiring correlation with iron studies.

• This finding supports checking iron studies as outlined above, particularly if ferritin is low. 5
• Isolated low MCHC without microcytosis is often clinically insignificant and may reflect laboratory measurement variability. [@general medicine knowledge@]

Critical Monitoring and Follow-Up

Schedule follow-up within 1-2 weeks to review HbA1c, iron studies, and repeat CBC, with earlier reassessment if symptoms develop or infection is suspected.

• Monitor for hypoglycemia risk if diabetes treatment is initiated, as elderly patients fail to perceive neuroglycopenic symptoms and have impaired counterregulatory responses. 2, 3
• Avoid glyburide and chlorpropamide if oral antidiabetic agents are prescribed, as these have high hypoglycemia risk in elderly patients. 2
• Review all medications for those associated with gastrointestinal bleeding (aspirin, NSAIDs, warfarin, clopidogrel), as 61% of elderly CKD patients with anemia are prescribed aspirin and 73% NSAIDs. 5
• Assess nutritional status, recent weight changes, and cognitive function, as malnutrition and frailty increase hypoglycemia risk and contribute to anemia in elderly hospitalized patients. 2, 3