Risk factors for new-onset CKD include older age, obesity, smoking history, diabetes, and hypertension. Other important risk factors include history of CVD, family history of CKD or ESRD, history of urinary tract infection or urinary obstruction, and systemic illnesses that may affect the kidney (eg, systemic lupus erythematosus, multiple myeloma).
Screening for Chronic Kidney Disease
Because of the age-related decline in kidney function, poor correlation between eGFR and pathologic findings on kidney biopsy, and concerns about the validity of GFR estimating equations in older populations, using eGFR to screen all older adults for CKD is not recommended. For an older patient, reduced eGFR (<60 mL/min/1.73 m2) should be interpreted in the context of the medical history and other lab abnormalities (eg, history of diabetic retinopathy, rate of eGFR decline, presence of elevated ACR) before a diagnosis of CKD is made.
Medical History and Physical Exam
Evaluation of CKD includes a thorough medical history, physical exam, and specific laboratory measures. The goal of this evaluation is to identify the underlying cause or causes, as multifactorial disease is common among older adults. A further goal is to identify CKD-related complications.
The medical history should include information on diabetes, hypertension, CVD, lower urinary tract disease and an evaluation for symptoms suggestive of vasculitis. Patients should be asked if they have a family history of CKD or ESRD. Typically, symptoms related to CKD do not occur until disease is advanced (eGFR <15 mL/min/1.73 m2) and include sleep disturbance, decreased attentiveness, nausea, vomiting, weight change, dyspnea, lower-extremity edema, fatigue, muscle cramps, peripheral neuropathy, and pruritus. A review of medications should also be performed to assess for medications that may be exacerbating kidney injury, such as nonsteroidal antiinflammatory drugs (NSAIDs), or medications that may be contraindicated or require dose reductions in CKD, such as hypoglycemic agents, oral and intravenous antimicrobials, antihypertensive agents, and opioids. Several resources are available to further assist in medication dosing and management for patients with CKD.
Because of the disproportionately higher rates of geriatric syndromes among older adults with CKD, comprehensive geriatric assessment for functional status, cognition, depression, and impaired mobility should be considered in this population.
The physical exam should include vital signs, orthostatic blood pressure and pulse, evaluation of volume status, and evaluation of skin and extremities.
Diagnostic testing should include urinalysis and random ACR. Twenty-four-hour urine collections for protein and creatinine clearance can be considered, but may be difficult for older adults. Blood work includes sodium, potassium, chloride, bicarbonate, blood urea nitrogen, creatinine, glucose, calcium, phosphorus, albumin, total protein, lipid profile, and complete blood count with differential. Additional tests may be indicated if the differential diagnosis includes causes other than diabetes or hypertension.
Evaluation for Underlying Causes
Prior to attributing reduced eGFR to CKD, an evaluation for reversible conditions causing acute kidney injury (AKI) should be considered. In addition, a rapid reduction in eGFR in a patient with known CKD should be considered AKI and evaluated promptly (see Figure 38–1).
Hypertension and diabetes are the 2 most common causes of CKD. However, multiple factors may contribute to the risk for CKD in the older population, including renal vascular disease, chronic urinary obstruction, systemic vasculitis, multiple myeloma, or intrinsic kidney disorders such as glomerulonephritis or nephrotic syndrome. High levels of proteinuria, abnormal urinary sediment with red or white blood cells, or rapidly progressive loss of kidney function should prompt work-up for causes other than diabetes or hypertension.