a. The role of human kidneys is to maintain homeostasis of electrolytes, minerals, pH, volume, blood pressure, metabolism of nutrients, waste products/toxins, and erythropoiesis.
b. Complex regulatory mechanisms maintain this homeostasis. Alterations in these mechanisms are the basis for nearly all renal diseases.
c. While nephrology topics are often considered confusing, a rational stepwise approach can help provide insight into what is occurring in the individual patient using the following constructs:
i. Understand normal renal physiology.
ii. Identify perturbations of normal homeostasis (e.g., hyperkalemia).
iii. Recognize the physiologic mechanism that has been disrupted to cause homeostatic perturbation (e.g., decreased renal potassium excretion due to mineralocorticoid deficiency).
iv. Associate known disease processes with the disrupted physiology (e.g., primary adrenal failure or angiotensin inhibitor use).
a. Many syndromes exist in nephrology, each with a set of causative diseases. Specific diseases are often capable of causing more than one syndrome.
In medicine, a “syndrome” refers to a set of clinical manifestations occurring together.
Table 36.1 Overview of Renal Syndromes
Key to Diagnosis
Examples of Causes
Acute kidney injury
Classify the cause as prerenal, postrenal, or intrarenal
Dehydration, shock, toxins, interstitial nephritis, obstruction due to enlarged prostate, RPGN, HUS/TTP
Classify the cause as renal or systemic
Primary renal diseases (e.g., membranous, focal segmental glomerulosclerosis, minimal change disease); systemic diseases (e.g., diabetes, amyloid, SLE)
Classify the cause as pauciimmune (ANCA) or immune complex deposition-related disease
Granulomatosis with polyangiitis, Goodpasture’s, afterpost streptococcal, infective endocarditis, SLE, MPGN, and IgA disease
Renal tubular acidosis
Classify the acidosis as type 1, 2, or 4
Amyloid, multiple myeloma, drugs (e.g., amphotericin), diabetes, Addison’s disease
ANCA = antineutrophil cytoplasmic antibody; GBM = glomerular basement membrane; HUS/TTP = hemolytic uremic syndrome/thrombotic thrombocytopenic purpura; IgA = immunoglobulin A; MPGN = membranoproliferative glomerulonephritis; RPGN = rapidly progressive glomerulonephritis; SLE = systemic lupus erythematosus.
b. Knowing the clinical manifestations and laboratory data for renal syndromes can help identify diseases. The differential diagnoses for most of the renal syndromes are easy to remember; match the diagnosis with the patient’s complaints and data, and you’ll be off to a great start!
Suggested Further Readings
Rosner MH, Perazella MA. Acute kidney injury in patients with cancer. N Engl J Med 2017;377:500–1.Find this resource:
Vassalotti JA, Centor R, Turner BJ, Greer RC, Choi M, Sequist TD. Practical approach to detection and management of chronic kidney disease for the primary care clinician. Am J Med 2016;129:153–62.e7.Find this resource: