What routine laboratory tests should be ordered for a 77‑year‑old woman with no known medical problems?

Routine Laboratory Testing for a 77-Year-Old Woman Without Known Medical Problems

For a healthy 77-year-old woman, order a complete blood count, comprehensive metabolic panel, lipid profile, 25-hydroxyvitamin D, TSH, and HbA1c or fasting glucose; most other routine laboratory tests are not indicated unless specific risk factors or symptoms are present.

Core Laboratory Panel

Complete Blood Count (CBC)

• Order a CBC to screen for anemia, which becomes increasingly prevalent with age and is associated with increased mortality and morbidity 1.
• Hemoglobin <120 g/L in women ≥18 years defines anemia and warrants further evaluation 1.
• The CBC also assesses bone marrow function through white blood cell and platelet counts; abnormalities in two or more cell lines warrant hematology consultation 1.
• Reference values for hemoglobin, platelet count, and white blood cell count in 80-year-olds differ from younger populations, so age-appropriate interpretation is important 2.

Comprehensive Metabolic Panel

• Order a comprehensive metabolic panel including electrolytes (sodium, potassium, chloride, bicarbonate), glucose, blood urea nitrogen, creatinine, calcium, and liver enzymes 3, 4.
• Serum creatinine and estimated GFR are essential to assess kidney function, as chronic kidney disease is common in this age group and affects anemia risk 1.
• Upper reference limits for creatinine and urea are significantly increased in elderly populations compared to younger adults 2.
• Alkaline phosphatase increases with age as a normal finding 5.
• Serum albumin may decrease with age, though this usually reflects chronic malnutrition rather than normal aging 5.

Diabetes Screening

• Screen with HbA1c or fasting plasma glucose at age 77, repeating every 3 years if normal 6, 4.
• HbA1c ≥6.5% (48 mmol/mol) or fasting plasma glucose ≥7.0 mmol/L (126 mg/dL) indicates diabetes 6.
• More frequent (annual) screening is warranted if the patient has risk factors such as BMI ≥25 kg/m², hypertension, dyslipidemia, or cardiovascular disease 6, 4.

Lipid Profile

• Order a fasting lipid panel (total cholesterol, LDL-C, HDL-C, triglycerides) to assess cardiovascular risk 4.
• Testing every 6–12 months is reasonable for those on lipid-modifying therapy or with cardiovascular risk factors 7.

Vitamin D and Bone Health

• Measure 25-hydroxyvitamin D as part of the evaluation for osteoporosis risk 3.
• Vitamin D deficiency is common in elderly populations and contributes to bone loss 3.

Thyroid Function

• Order TSH screening in this age group, as thyroid dysfunction becomes more prevalent with age 8, 4.
• The proportion of physicians ordering TSH for healthy women aged 55 years increased from 14% in 1978 to 57% in 2004, reflecting growing recognition of its importance 9.

Additional Considerations Based on Risk Factors

Iron Studies (If Anemia Present)

• If anemia is detected, measure serum ferritin and transferrin saturation to assess iron status 1.
• In nondialysis patients not on erythropoietic agents, ferritin <25 ng/mL in males and <11 ng/mL in females suggests insufficient iron stores 1.
• Iron deficiency in the absence of menstrual losses should prompt evaluation for gastrointestinal bleeding 1.

Intact Parathyroid Hormone (PTH)

• Measure intact PTH if osteoporosis screening is performed or if calcium abnormalities are detected 3.
• PTH assessment is part of the comprehensive evaluation for secondary causes of osteoporosis 3.

24-Hour Urine Collection

• A 24-hour urine collection for calcium, sodium, and creatinine is indicated only if osteoporosis is diagnosed and must be performed after vitamin D repletion and adequate calcium intake (1,000–1,200 mg/day) for at least 2 weeks 3.

Tests NOT Routinely Indicated

Urinalysis

• Do not order routine urinalysis in asymptomatic patients; the proportion of physicians ordering UA for healthy adults has appropriately declined from 93% in 1978 to 44% in 2004 9.
• Routine admission urinalysis in hospitalized patients has minimal impact on care (only 0.5% led to treatment changes) 10.

Electrocardiogram

• Do not order routine ECG for asymptomatic patients; physician ordering has declined from 63% in 1978 to 29% in 2004 for healthy women aged 55 years 9.

Coagulation Studies

• Do not order prothrombin time or partial thromboplastin time without specific clinical indications 10.

Tumor Markers

• Do not order cancer screening blood tests such as CA-125 or CEA in asymptomatic patients without specific risk factors 11.

Common Pitfalls to Avoid

• Do not order extensive "routine" laboratory panels without clinical indication; 45% of routine admission tests in one study were ordered without recognizable medical indications, and only 0.5% led to treatment changes 10.
• Do not interpret laboratory values using reference ranges derived from younger populations; several parameters (creatinine, urea, iron, albumin, alkaline phosphatase) have age-dependent reference intervals 2, 5.
• Do not assume abnormal values are "normal for age"; most laboratory values in healthy elderly persons fall within normal ranges, and significantly abnormal results should raise suspicion of underlying disease 5.
• Do not order screening tests that lack evidence of benefit; 71.6% to 90.7% of physicians in one survey ordered screening laboratory tests not recommended by the U.S. Preventive Services Task Force 12.

Procedural Screening (Not Laboratory Tests)

While not laboratory tests, the following procedural screenings are appropriate at age 77:

• Mammography should be offered if the patient is in good health with life expectancy ≥10 years 13.
• Colorectal cancer screening should be individualized based on health status and prior screening history; routine screening is recommended through age 75, with selective screening ages 76–85 13.
• Cervical cancer screening should be discontinued if adequate prior screening (≥3 consecutive negative Pap tests or ≥2 consecutive negative HPV+Pap co-tests in the past 10 years) has been documented 13.
• Bone density testing (DEXA) is recommended for all women ≥65 years 3, 13.