PART 2: Cardinal Manifestations and Presentation of Diseases
SECTION 7 Alterations in Renal and Urinary Tract Function
45 Fluid and Electrolyte Disturbances
 | Figure 45-1 Circulating levels of vasopressin (AVP) in response to changes in osmolality. Plasma vasopressin becomes detectable in euvolemic, healthy individuals at a threshold of ∼285 mOsm/Kg, above which there is a linear relationship between osmolality and circulating AVP. The vasopressin response to osmolality is modulated... |
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 | Figure 45-2 The renal concentrating mechanism. Water, salt, and solute transport by both proximal and distal nephron segments participates in the renal concentrating mechanism (see text for details). Diagram showing the location of the major transport proteins involved; a loop of Henle is depicted on the left, a collecting duct on... |
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 | Figure 45-3 Vasopressin and the regulation of water permeability in the renal collecting duct. Vasopressin binds to the type 2 vasopressin receptor (V2R) on the basolateral membrane of principal cells, activates adenylyl cyclase (AC), increases intracellular cyclic adenosine monophosphatase (cAMP), and stimulates protein kinase A... |
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 | Figure 45-4 Sodium, water, and potassium transport in principal cells (PC) and adjacent a-intercalated cells (B-IC). The absorption of Na+ via the amiloride-sensitive epithelial sodium channel (ENaC) generates a lumen-negative potential difference that drives K+ excretion through the apical secretory K+... |
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 | Figure 45-5 The diagnostic approach to hyponatremia. [From S Kumar, T Berl: Diseases of water metabolism, in Atlas of Diseases of the Kidney, RW Schrier (ed). Philadelphia, Current Medicine, Inc, 1999; with permission.] |
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 | Figure 45-6 The diagnostic approach to hypernatremia. ECF, extracellular fluid. |
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 | Figure 45-7 The diagnostic approach to hypokalemia. See text for details. BP, blood pressure; DKA, diabetic ketoacidosis; FHPP, familial hypokalemic periodic paralysis; FH-I, familial hyperaldosteronism type I; GI, gastrointestinal; HTN, hypertension; PA, primary aldosteronism; RAS, renal artery stenosis; RST, renin-secreting... |
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 | Figure 45-8 The diagnostic approach to hyperkalemia. See text for details. ACE-I, angiotensin converting enzyme inhibitor; acute GN, acute glomerulonephritis; ARB, angiotensin II receptor blocker; ECG, electrocardiogram; ECV, effective circulatory volume; GFR, glomerular filtration rate; LMW heparin, low-molecular-weight heparin;... |
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