Chapter 045. Azotemia and Urinary Abnormalities (Part 1) Harrison's Internal Medicine > Chapter 45. Azotemia and Urinary Abnormalities Azotemia and Urinary Abnormalities: Introduction Normal kidney functions occur through numerous cellular processes to maintain body homeostasis. Disturbances in any of these functions can lead to a constellation of abnormalities that may be detrimental to survival. The clinical manifestations of these disorders will depend upon the pathophysiology of the renal injury and will often be initially identified as a complex of symptoms, abnormal physical findings, and laboratory changes that together make possible the identification of specific syndromes. These renal syndromes (Table 45-1) may arise as the consequence of a systemic illness or can occur as a primary renal disease. Nephrologic syndromes usually consist of several elements that reflect the underlying pathologic processes. The duration and severity of the disease will affect these findings and typically include one or more of the following: (1) disturbances in urine volume (oliguria, anuria, polyuria); (2) abnormalities of urine sediment [red blood cells (RBC); white blood cells, casts, and crystals]; (3) abnormal excretion of serum proteins (proteinuria); (4) reduction in glomerular filtration rate (GFR) (azotemia); (5) presence of hypertension and/or expanded total body fluid volume (edema); (6) electrolyte abnormalities; or (7) in some syndromes, fever/pain. The combination of these findings should permit identification of one of the major nephrologic syndromes (Table 45-1) and will allow differential diagnoses to be narrowed and the appropriate diagnostic evaluation and therapeutic course to be determined. Each of these syndromes and their associated diseases are discussed in more detail in subsequent chapters. This chapter will focus on several aspects of renal abnormalities that are critically important to distinguishing among these processes: (1) reduction in GFR leading to azotemia, (2) alterations of the urinary sediment and/or protein excretion, and (3) abnormalities of urinary volume. Table 45-1 Initial Clinical and Laboratory Data Base for Defining Major Syndromes in Nephrology Syndromes Important Clues to Diagnosis Findings That Are Common Locati on of Discussion of Disease- Causing Syndrome Acute or rapidly progressive renal failure Anuria Oliguria Documented recent decline in GFR Hypertensi on, hematuria Proteinuria , pyuria Casts, edema Chaps. 273, 277, 279, 283 Acute nephritis Hematuria, RBC casts Azotemia, oliguria Edema, Proteinuria Pyuria Circulatory congestion Chap. 277 hypertension Chronic renal failure Azotemia for >3 months Prolonged symptoms or signs of uremia Symptoms or signs of renal osteodystrophy Kidneys reduced in size bilaterally Broad casts in urinary sediment Proteinuria Casts Polyuria, nocturia Edema, hypertension Electrolyte disorders Chaps. 272, 274 Nephrotic syndrome Proteinuria >3.5 g per 1.73 m 2 per Casts Lipiduria Chap. 277 24 h Hypoalbumine mia Edema Hyperlipidemi a Asymptomati c urinary abnormalities Hematuria Proteinuria (below nephrotic range) Sterile pyuria, casts Chap. 277 Urinary tract infection/pyelonephr itis Bacteriuria >10 5 colonies per milliliter Other Hematuria Mild azotemia Mild Chap. 282 infectious agent documented in urine Pyuria, leukocyte casts Frequency, urgency Bladder tenderness, flank tenderness proteinuria Fever Renal tubule defects Electrolyte disorders Polyuria, nocturia Renal calcification Large kidneys Renal transport Hematuria "Tubular" proteinuria (<1 g/24 h) Enuresis Chaps. 278, 279 defects Hypertension Systolic/diastol ic hypertension Proteinuria Casts Azotemia Chaps. 241, 280 Nephrolithias is Previous history of stone passage or removal Previous history of stone seen by x-ray Renal colic Hematuria Pyuria Frequency, urgency Chap. 281 Urinary tract obstruction Azotemia, oliguria, anuria Polyuria, Hematuria Pyuria Enuresis, Chap. 283 nocturia, urinary retention Slowing of urinary stream Large prostate, large kidneys Flank tenderness, full bladder after voiding dysuria Note: GFR; glomerular filtration rate; RBC, red blood cell. . Chapter 045. Azotemia and Urinary Abnormalities (Part 1) Harrison's Internal Medicine > Chapter 45. Azotemia and Urinary Abnormalities Azotemia and Urinary Abnormalities: . leading to azotemia, (2) alterations of the urinary sediment and/ or protein excretion, and (3) abnormalities of urinary volume. Table 45-1 Initial Clinical and Laboratory Data Base for Defining Major. cells, casts, and crystals]; (3) abnormal excretion of serum proteins (proteinuria); (4) reduction in glomerular filtration rate (GFR) (azotemia) ; (5) presence of hypertension and/ or expanded total