The kidneys are responsible for several vital homeostatic processes, including the excretion of nitrogenous waste products, the regulation of fluid volume and electrolytes, acid–base balance, and the production of hormones important for blood pressure regulation, erythropoiesis, and bone metabolism. They are frequently affected by disease, both acute (occurring over days to weeks) and chronic (occurring over months to years). Acute kidney injury (AKI), formerly known as acute renal failure, has become an increasingly common cause of hospitalization, with an incidence of 5% to 7% among hospitalized patients. Chronic kidney disease (CKD) reportedly affects 13% of adults in the United States, and is associated with significant morbidity, mortality, and expense. The recent advent of automatic reporting of estimated glomerular filtration rate (eGFR) with serum creatinine by hospital laboratories has resulted in more patients being identified as having impaired renal function. In order to provide the highest level of care for patients presenting with acute or CKD, the clinician should have a strong understanding of the fundamental issues relevant to their evaluation and management.
EVALUATION OF THE RENAL PATIENT
HISTORY AND PHYSICAL EXAMINATION
The evaluation of the patient with kidney disease begins with a thorough history and physical examination. The clinician should identify whether the renal disease is acute or chronic. If the patient’s previous medical records are available, this can be determined by quickly reviewing prior laboratory testing, with particular attention given to serum creatinine, blood urea nitrogen, and urinalyses. Patients who present with AKI should be questioned about recent symptoms (eg, vomiting, diarrhea, edema, difficulty voiding, decreased appetite, weight changes) and events (eg, changes in oral intake, new medications, nonsteroidal anti-inflammatory drug [NSAID] use, intravenous contrast administration, recent colonoscopy) that may help narrow the differential diagnosis of AKI. Symptoms such as fever, rashes, arthralgias, epistaxis, and hemoptysis suggest an underlying inflammatory condition such as vasculitis. For patients who develop AKI during their hospitalization, recent hospital events—including episodes of hypotension, recent diagnostic and therapeutic procedures, and initiation of new medications—should be reviewed. All patients presenting with AKI or CKD should be questioned about symptoms associated with uremia, including fatigue, nausea, vomiting, pruritus, metallic taste, lethargy, and confusion, since these symptoms may indicate the need for dialysis.
Patients should be asked whether they have a prior history of kidney disease or other relevant systemic diseases, such as diabetes and hypertension. In patients with CKD, who may or may not be presenting with an acute kidney-related problem, the clinician should establish the chronicity, severity, and cause of the underlying kidney disease. In patients with end-stage renal disease (ESRD), information about the patient’s nephrologist, outpatient dialysis unit, and regular dialysis schedule (including the timing of the last dialysis session) should be obtained and conveyed to the clinicians and other health care providers who will be facilitating the patient’s dialysis during the hospitalization. The clinician should also obtain a complete ...