Figure 34
Renal potassium handling. More than half of filtered potassium is passively reabsorbed by the end of the proximal convolted tubule PCT . Potassium is then added to tubular fluid in the descending limb of Henle's loop see below . The major site of active potassium reabsorption is the thick ascending limb of the loop of Henle TAL , so that, by the end of the distal convoluted tubule DCT , only 10 to 15 of filtered potassium remains in the tubule lumen. Potassium is secreted mainly by the...
Operational Characteristics
Pathways of thrombogenesis in extracorporeal circuits. Modified from Lindhout 8 with permission. n ,.1 in-, 1 Membrane Patient I Dialyzer J Uremia gt C J Geometry Drug therapy -V Manufacture Dialyzer preparation Anticoagulation Blood flow access Dialyzer preparation Anticoagulation Blood flow access Factors influencing dialysis-related thrombogenicity. One of the major determinants of the efficacy of any dialysis procedure in acute renal failure ARF is the ability to maintain a functioning...
Figure 39
Diagnostic approach to hypokalemia hypokalemia due to renal losses with normal acid-base status or metabolic acidosis. Hypokalemia is occasionally observed during the diuretic recovery phase of acute tubular necrosis ATN or after relief of acute obstructive uropathy, presumably secondary to increased delivery of sodium and water to the distal nephrons. Patients with acute monocytic and myelomonocytic leukemias occasionally excrete large amounts of lysozyme in their urine. Lysozyme appears to...
Hypokalemia Treatment
Treatment of hypokalemia estimation of potassium deficit. In the absence of stimuli that alter intracellular-extracellular potassium distribution, a decrease in the serum potassium concentration from 3.5 to 3.0 mEq L corresponds to a 5 reduction 175 mEq in total body potassium stores. A decline from 3.0 to 2.0 mEq L signifies an additional 200 to 400-mEq deficit. Factors such as the rapidity of the fall in serum potassium and the presence or absence of symptoms dictate the aggressiveness of...
Hypokalemia Diagnostic Approach
Overview of diagnostic approach to hypokalemia hypokalemia without total body potassium depletion. Hypokalemia can result from transcellular shifts of potassium into cells without total body potassium depletion or from decreases in total body potassium. Perhaps the most dramatic examples occur in catecholamine excess states, as after administration of l adreneric receptor P2AR agonists or during stress. It is important to note that, during some conditions eg, ketoaci-dosis , transcellular...
Fernando Liao Julio Pascual
There are many causes more than fifty are given within this present chapter that can trigger pathophysiological mechanisms leading to acute renal failure ARF . This syndrome is characterized by a sudden decrease in kidney function, with a consequence of loss of the hemostatic equilibrium of the internal medium. The primary marker is an increase in the concentration of the nitrogenous components of blood. A second marker, oliguria, is seen in 50 to 70 of cases. In general, the causes of ARF have...
Figure 327
Clinical application of the transtubular potassium gradient TTKG . The TTKG in normal persons varies much but is genarally within the the range of 6 to 12. Hypokalemia from extrarenal causes results in renal potassium conservation and a TTKG less than 2. A higher value suggests renal potassium losses, as through hyperaldostero-nism. The expected TTKG during hyperkalemia is greater than 10. An inappropriately low TTKG in a hyperkalemic patient suggests hypoaldosteronism or a renal tubule defect....
Relative Advantages And Disadvantages Of Crrt Ihd And Pd
Advantages and disadvantages of dialysis techniques. CRRT continuous renal replacement therapy IHD intermit-tent hemodialysis PD peritoneal dialysis. Patient Indication for dialysis Presence of multiorgan failure Access Mobility and location of patient Anticipated duration of therapy Dialysis process Components eg, membrane, anticoagulation Type intermittent or continuous Efficacy for solute and fluid balance Complications Outcome Nursing and other support Availability of machines Nursing...
Figure 129
Pathogenesis of hypernatremia. The renal concentrating mechanism is the first line of defense against water depletion and hyper-osmolality. When renal concentration is impaired, thirst becomes a very effective mechanism for preventing further increases in serum osmolality. The components of the normal urine concentrating mechanism are shown in Figure 1-2. Hypernatremia results from disturbances in the renal concentrating mechanism. This occurs in interstitial renal disease, with administration...
Gastrointestinal Absorption of Calcium
Gastrointestinal absorption of dietary calcium Ca Gastrointestinal absorption of dietary calcium Ca Normal dietary Ca intake 1000 mg 25 mmol per day Normal dietary Ca intake 1000 mg 25 mmol per day Gastrointestinal absorption of dietary calcium Ca . The normal recommended dietary intake of Ca for an adult is 800 to 1200 mg d 20-30 mmol d . Foods high in Ca content include milk, dairy products, meat, fish with bones, oysters, and many leafy green vegetables eg, spinach and collard greens ....
Approaches For Fluid Management In Crrt
Approaches for fluid management in continuous renal replacement therapy CRRT . CRRT techniques are uniquely situated in providing fluid regulation, as fluid management can be achieved with three levels of intervention 16 . In Level 1, the ultrafiltrate UF volume obtained is limited to match the anticipated needs for fluid balance. This calls for an estimate of the amount of fluid to be removed over 8 to 24 hours and subsequent calculation of the ultrafiltration rate. This strategy is similar to...
Ravindra L Mehta
Over the last decade, significant advances have been made in the availability of different dialysis methods for replacement of renal function. Although the majority of these have been developed for patients with end-stage renal disease, more and more they are being applied for the treatment of acute renal failure ARF . The treatment of ARF, with renal replacement therapy RRT , has the following goals 1 to maintain fluid and electrolyte, acid-base, and solute homeostasis 2 to prevent further...
Acute Rejection
DIAGNOSTIC POSSIBILITIES IN TRANSPLANT-RELATED ACUTE RENAL FAILURE Diagnostic possibilities in transplant-related acute renal failure. 1. Acute cell-mediated rejection 2. Delayed-appearing antibody-mediated rejection 4. Cyclosporine or FK506 toxicity 8. Post-transplant lymphoproliferative disorder Diagnosis of rejection in the Banff classification makes use of two basic lesions, tubulitis and intimal arteritis. The 1993-1995 Banff classification depicted in this figure is the standard in use in...
Composition Of Replacement Fluid And Dialysate For Crrt
Composition of dialysate and replacement fluids used for continuous renal replacement therapy CRRT . One of the key features of any dialysis method is the manipulation of metabolic balance. In general, this is achieved by altering composition of dialysate or replacement fluid . Most commercially available dialysate and replacement solutions have lactate as the base however, bicarbonate-based solutions are being utilized more and more 17,18 . Replacement 17 mL min Prefilter Prefilter Effect of...
Rick G Schnellmann Katrina J Kelly
Humans are exposed intentionally and unintentionally to a variety of diverse chemicals that harm the kidney. As the list of drugs, natural products, industrial chemicals and environmental pollutants that cause nephrotoxicity has increased, it has become clear that chemicals with very diverse chemical structures produce nephrotoxicity. For example, the heavy metal HgCl2, the myco-toxin fumonisin B1, the immunosuppresant cyclosporin A, and the aminoglycoside antibiotics all produce acute renal...
Ischemia Induced Proximal Tubule Cell Alterations
Ischemia induced proximal tubule cell alterations. 1. Microvilli fusion, internalization, fragmentation and luminal shedding resulting in loss of surface membrane area and tubular obstruction 2. Loss of surface membrane polarity for lipids and proteins 3. Junctional complex dissociation with unregulated paracellular permeability backleak 1. Polymerization of actin throughout the cell cytosol 2. Disruption and delocalization of F-actin structures including stress fibers, cortical actin 3....
Renal Handling of Calcium
Glomerular filtration of calcium Ca . Total serum Ca consists of ionized, protein bound, and complexed fractions 47.5 , 46.0 , and 6.5 , respectively . The complexed Ca is bound to molecules such as phosphate and citrate. The ultrafilterable Ca equals the total of the ionized and complexed fractions. Normal total serum Ca is approximately 8.9 to 10.1 mg dL about 2.2-2.5 mmol L . Ca can be bound to albumin and globulins. For each 1.0 gm dL decrease in serum albumin, total serum Ca decreases by...
Renal Handling of Magnesium
The glomerular filtration of magnesium Mg . Total serum Mg consists of ionized, complexed, and protein bound fractions, 60 , 7 , and 33 of total, respectively. The complexed Mg is bound to molecules such as citrate, oxalate, and phosphate. The ultrafil-terable Mg is the total of the ionized and complexed fractions. Normal total serum Mg is approximately 1.7 to 2.1 mg dL about 0.70-0.90 mmol L 1,2,7-9,11,12 . The renal handling of magnesium Mg2 . Mg is filtered at the glomerulus, with the...
Figure 12
Determinants of the renal concentrating mechanism. Human kidneys have two populations of nephrons, superficial and juxtamedullary. This anatomic arrangement has important bearing on the formation of urine by the countercurrent mechanism. The unique anatomy of the nephron 1 lays the groundwork for a complex yet logical physiologic arrangement that facilitates the urine concentration and dilution mechanism, leading to the formation of either concentrated or dilute urine, as appropriate to the...
Hyperkalemia Diagnostic Approach
Approach to hyperkalemia hyperkalemia without total body potassium excess. Spurious hyperkalemia is suggested by the absence of electrocardiographic ECG findings in patients with elevated serum potassium. The most common cause of spurious hyperkalemia is hemolysis, which may be apparent on visual inspection of serum. For patients with extreme leukocytosis or thrombocytosis, potassium levels should be measured in plasma samples that have been promptly separated from the cellular components since...
Acute Renal Failure Cellular Features of Injury and Repair
Kevin T. Bush Hiroyuki Sakurai Tatsuo Tsukamoto Sanjay K. Nigam Although ischemic acute renal failure ARF is likely the result of many different factors, much tubule injury can be traced back to a number of specific lesions that occur at the cellular level in ischemic polarized epithelial cells. At the onset of an ischemic insult, rapid and dramatic biochemical changes in the cellular environment occur, most notably perturbation of the intracellular levels of ATP and free calcium and increases...
References Cmt
1. Zager RA, Gmur DJ, Bredl CR, et al. Regional responses within the kidney to ischemia Assessment of adenine nucleotide and catabolite profiles. Biochim Biophys Acta 1990, 1035 29-36. 2. Hays SR Ischemic acute renal failure. Am J Med Sci 1992, 304 93-108. 3. Toback FG Regeneration after acute tubular necrosis. Kidney Int 1992, 41 226-246. 4. Liu S, Humes HD Cellular and molecular aspects of renal repair in acute renal failure. Curr Opin Nephrol Hypertension 1993, 2 618-624. 5. Doctor RB,...
Of Acute Renal Failure
Urine diagnostic indices see Fig. 12-16 Consider need for further evaluation for obstruction Ultrasonography, computed tomography, or magnetic resonance imaging Consider need for additional blood tests Vasculitis glomerulopathy human immunodeficiency virus infections, antineu-trophilic cytoplasmic antibodies, antinuclear antibodies, serologic tests for hepatitis, systemic bacterial endocarditis and streptococcal infections, rheumatoid factor, complement, cryoglobins Plasma cell disorders urine...
Recommendation For Initial Dialysis Modality For Acute Renal Failure Arf
Recommendation for initial dialysis modality for acute renal failure ARF . Patients with multiple organ failure MOF and ARF can be treated with various continuous therapies or IHD. Continuous therapies provide better hemodynamic stability however, if not monitored carefully they can lead to significant volume depletion. In general, hemodynami-cally unstable, catabolic, and fluid-overloaded patients are best treated with continuous therapies, whereas IHD is better suited for patients who require...
Categorization of Causes of Acute Renal Failure
Acute renal failure ARF . This figure depicts the most commonly used schema to classify and diagnostically approach the patient with ARF 1, 6, 9 . The most common general cause of ARF 60 to 70 of cases is prerenal factors. Prerenal causes include those secondary to renal hypoperfusion, which occurs in the setting of extracellular fluid loss eg, with vomiting, nasogastric suctioning, gastrointestinal hemorrhage, diarrhea, burns, heat stroke, diuretics, glucosuria , sequestration of extracellular...
References Mzz
Agus ZS Phosphate metabolism. In UpToDate, Inc Edited by Burton D. Rose, 1998. Hruska KA, Slatopolsky E Disorders of phosphorus, calcium, and magnesium metabolism. In Diseases of the Kidney, edn 6. Edited by Schrier RW, Gottschalk CW. Boston Little and Brown 1997. Levi M, Knochel JP The management of disorders of phosphate metabolism. In Therapy of Renal Diseases and Related Disorders. Edited by Massry SG, Suki WN. Boston, Martinus Nijhoff 1990. Levi M, Cronin RE, Knochel JP Disorders of...
Figure 11
Principles of normal water balance. In most steady-state situations, human water intake matches water losses through all sources. Water intake is determined by thirst see Fig. 1-12 and by cultural and social behaviors. Water intake is finely balanced by the need to maintain physiologic serum osmo-lality between 285 to 290 mOsm kg. Both water that is drunk and that is generated through metabolism are distributed in the extracellular and intracellular compartments that are in constant...
Sumit Kumar Tomas Berl
The maintenance of the tonicity of body fluids within a very narrow physiologic range is made possible by homeostatic mechanisms that control the intake and excretion of water. Critical to this process are the osmoreceptors in the hypothalamus that control the secretion of antidiuretic hormone ADH in response to changes in tonicity. In turn, ADH governs the excretion of water by its end-organ effect on the various segments of the renal collecting system. The unique anatomic and physiologic...