Computed Tomography

CT is a digital cross-sectional imaging technique capable of detecting subtle variations in X-ray attenuation by different tissues. Data samples are obtained by moving the source around the patient at a given cross section of the body while measuring attenuation values along the X-ray beam. A computer calculates the average X-ray attenuation of all tissues within a specific volume element or voxel and represents it by a resulting number (CT number or pixel value). All CT numbers are referenced...

Diabetic Ketoacidosis

DKA is the metabolic cons equence of a lack of actions of insulin and it is characterized by the accumulation of glucose and ketoacids in the body 16 . The precipitating illness and the complications of this metai bolic disturbance can be life-threatening. The changes in the hepatic metabolism that lead to overproduction of ketoacids are depicted in Figures 3 and 16. DKA may be the first indication of undiagnosed type 1 diabetes mellitus in children. The precipitating causes include an...

Info

Clusters Bubbles Urine

False negative results may occur due to high ascorbic acid content False negative results may occur due to high ascorbic acid content binuria and myoglobinuria, after eating beets, and during rifampin therapy. Yellow to brown urine is due to bile pigments in jaundiced patients. Urine of normal color upon voiding that darkens with time suggests porphyria (porphobilinogen), melanoma (melanogen), or alkaptonuria (homogentisic acid) in the appropriate clinical setting. Many drugs also influence the...

Echo Genie Lesion Of Kidney

Sagittal sonogram of the right kidney demonstrates the central hyperechoic sinus echo CT (S) surrounded by the hy-poechoic renal parenchyma (P). The medullary pyramids are hypoechoic and located peripheral to the sinus (arrows). Figure 5. Normal kidney. Sagittal sonogram of the right kidney demonstrates the central hyperechoic sinus echo CT (S) surrounded by the hy-poechoic renal parenchyma (P). The medullary pyramids are hypoechoic and located peripheral to the sinus...

Radionuclide Studies

147 Bajen MT, Martin-Comin J, Mora J, Castelao A, Grinyo JM, Gonzalez A, Puchal R 1997 MAG3 renogram deconvolution in kidney transplantation utility of the measurement of initial tracer uptake. J Nucl Med 38 1295-1299 148 Blaufox MD, VolterraniD, ThomsenHS, Taylor A, Russell C, Piepsz A, Fommei E, Bubeck B, Aurell M1996 Report of the radionuclides in nephrourol-ogy committee on renal clearance. J Nucl Med 37 1883-1890 149 Clorius JH, van Kaick G, Denk S, Schmidlin P Zuna I, Hupp T1997 The...

Alcoholic Ketoacidosis

Alcoholic ketoacidosis is seen foliowing binge drinking of large amounts of ethanol complicated by poor food intake and vomiting (usually due to alcohol-induced gastritis) 113, 114 . The lack of food iniake and the ECF volume depletion lead to suppression of insulin secretion via an a-adrenergic effect 115 . This combination of hormonal changes both increases lipolysis in adipose tissue (stimulation of hormone-sensitive lipase) and diminishes hepatic lipogenesis (inhibition of hepatic...

Llactic Acidosis

Blood Diffusion Acidosis

L-Lactic acidosis may be classified into two major categories depending on whether or not the supply of oxygen is matched to tissue demands for energy metabolism. In type AL-lactic acidosis, the production of L-lactic acid is increased and its removal impaired because of tissue hypoxia (Figure 19). In contrast, in type B L-lactic acidosis, hepatic removal of L-lactate is impaired for reatons other than hypoxia 117 (Table 17). Type AL-lactic acidosis is particularly frustrating to treat because...

Creatinine Clearance

Ccr is the most widely used clinical estimate of GFR. Creatine is derived from the metabolism of creatine in skeletal muscle and from dietary meat intake, with about 1.6 of the creatine pool converted to creatinine. It is freely filtered at the glomerulus and not reabsorbed or metabolized. However, approximately 15 of the urinary creatinine is de rived from tubular secretion. Its overall excretion rate is 15 - 20 mg kg day in females and 20 - 25 mg kg day in males. Although creatinine...

Excretion of NH4

CONCEPT 3 Generation of new HCO3-without H occurs when NH4 is excreted. To generate new HCO3-, glutamine, must be metabo-ized in the cells of the proximal convo-uted tubule PCT to yield NH4 and the a-ketoglutarate a-KG anion 15 . Metabolism of a-KG to neuiral end products CO2 or glucose yields HCO3 that are added to the body. Never-he-ess, for a net gain of HCO3-, NH4 must be made into an end product of metabolism by being excreted in the urine Figure 5 . The rate of excretion of NH4 can be...

Urological Procedures

Major indications for urological interventions encompass abnormal bladder function, suspected lesions benign or malignant , presumed lower tract bleeding, intra extralumi-nal ureteric lesions, the need for precise definition of the collecting system, and evaluation of vesicoureteric reflux. Urological procedures of interest to the nephrologist include cystoscopy, retrograde and antegrade pyelography, cystourethrogaphy, and upper tract endoscopy and lithotripsy. Retrograde pyelography Contrast...

Magnetic Resonance Imaging

Perinephric Fat

MRI is based on the spontaneous alignment of magnetic moments of the nuclei contained in tissues when an external electromagnetic field is applied. Because H is abundant in the human body and has a high gyromagnetic ratio, MRI is almost exclusively carried out with protons. Images are produced by applying multiple radiofrequency signals 256 -512 pulses over several minutes. Fat satura- Figure 14. Renal trauma. Precontrast CT reveals a hyperdense perinephric collection secondary to hemorrhage H...

Serum Complement Levels

The serum complement battery routinely includes assessment of CH50, C3, and C4 levels. CH50 is assayed by incubating serum samples with sheep RBCs sensitized with rabbit anti-red-blood-cell antibodies. One CH50 unit is defined as the amount required to lyse 50 of RBCs in the assay. A normal CH50 indicates that complements 1 - 9 are present, but is less sensitive in screening for C4 deficiency. A low CH50 identifies patients with hereditary or acquired deficiencies. C3 and C4 are measured by...

References

1 Voet D, Voet HG 1990 Biochemi stry. Wiley amp Sons, New York 2 Halperin ML, Rolleston FS 1993 Clinical detective stories a problem-based approach to clinical cases in energy and acid-base metaboiism. Portland Press, London 3 Steinmetz PR, Andersen OS 1982 Electrogenic proton transport in epithelial membranes. J Membrane Biol 65 155-174 4 Vasuvattakul S, Warner LC, Halperin ML 1992 Quantitative role of the intracellular bicarbonate buffer system in response to an acute acid load. Am J Physiol...

Importance of the Urine pH to Avoid Kidney Stone Formation

And Uric Acid

All the water-soluble waste products and all the ions and water ingested in excess of needs must be excreted in the urine without forming precipitates. One of the most important renal physiological functions is to excrete urine with a composition that makes ions and organic materials sufficiently soluble to avoid kidney stone formation. Key to this aim is to have independent regulation of the urine pH -select a value that is close to 6.0 to achieve this aim 45 Figure 10 . Excreting urine at...

Physiology of K Homeostasis

Insulin Shift Hyperkalemia

K are the most abundant cations in the body. Close to 98 of K 4000 mmol in a typical adult exist in the intracellular fluid ICF compartment and close to 60 mmol are in the extracellular fluid ECF compartment. The ratio of the concentration, K , in the ICF compartment to that in the ECF compartment reflects the resting membrane potential RMP . The RMP must remain relatively constant in the face of a daily intake of K that is roughly equal to the total content of K in the ECF. Regulation of K...

Metabolic Alkalosis

Alkalosis Flow Chart

There is not enough K in the ECF to account for the magnitude of its negative balance. The striking feature is that on mass balance, there was near-equimolar losses of Cl- and K with little change in the mass balance for Na . Similar observations were made in experiments in animals. Mass balance data from human and animal experiments are summarized in Table 6. Having established that the mass balance during this selective HCl loss or so-called selective Cl -depletion alkalosis, which is, of...

Likelihood of a Major Threat to Life

Disorders that cause metabolic acidosis can harm patients through a variety of mechanisms Table 8 . We shall consider 4 maj or categories In essence, the only condition associated with extremely rapid net production of acid is L-lactic aridosis due to hypoxia Table 2 . The threat here is that ATP may not be regenerated quickly enough. Quantitatively, the rate of acid addition can be approximated by Table 9. Causes of metabolic acidosis associated with hyperkalemia. Specific disorders causing...

Metabolic Acidosis

Definition Inmetabolic acidosis, there is a fall in the plasma pH and PHCo3. Because other primary acid-base abnormalities may coexist, the plasma pH and or PHCO3 may not be low. For example, if respiratory alkalosis is also present, the pH will be higher if metabolic alkalosis is also present, the PHCO3 and plasma pH may not be low. Therefore clues from the history and physical examination together with additional laboratory data plasma ani on gap must be int egrated to know whether metabolic...

Serum Creatinine and Blood Urea Nitrogen Concentration

Serum creatinine and blood urea nitrogen BUN concentrations are most commonly used as estimates of GFR because of ease of use, wide availability, and considerable practical value in patient care. Serum creatinine concentration is the recommended test for screening asymptomatic adults for overt renal dysfunction. However, the sensitivity for detecting mild decreases in true inulin GFR 50 - 90 mL min is not very high. Among patients with decreased renal function documented by inulin clearance, 25...

Complications of Renal Biopsy

It is useful to divide complications of percutaneous renal biopsy into major and minor, as detailed in Table 8. Complication rates must be interpreted both in the context of the series size as well as the method of percutaneous biopsy. The largest reported series in the literature did not use real time ultrasound monitoring or smaller 15- or 18-gauge spring-loaded needles. More recent series using these approaches report significantly fewer complications. The most common major complication of...

Buffering of H by Intracellular Proteins

Phco3 When the Phco3 is very low, there is little HCO3- in the ECF compartment to buffer newly added H so most of these H will now be bound to intracellular proteins. Hence when the PHCO3 is very low and if there is a possibility that it may decline even further, this may be an indication to administer NaHCO3. In this regard, it is also important to note the impact of very small absolute changes in the PHCO3 when this concentration is very low to begin with. For instance, if the fall in the...

Renal Biopsy

172 Adu D 1996 The nephrotic syndrome does renal biopsy affect management Nephrol Dial Transplant 11 12-14 173 Alcazar R, de la Torre M, Peces R 1996 Symptomatic intrarenal arteriovenous fistula detected 25 years after percutaneous renal biopsy. Nephrol Dial Transplant 11 1346-1348 174 CastoldiMC, DelMOro RM, Urano ML, Perrario F Porri MT, Maldifassi P, Amico GD, Casolo F 1994 Sonography after renal biopsy assessment of its role in 230 consecutive cases. Abdom Imaging 19 72-77 175 Christensen...

Specific Causes of Hypokalemia

Gitelman Liddle And Bartter Syndrome

A summary of the causes of hypokalemia is provided in Table 4 and Figure 11. We shall comment only briefly on some of these disorders, either because they are common or because new strides have been made in understanding their pathophysiology. Very low Mg2 diet Bartter's Mg malabsorption syndrome Drugs e.g., cisplatin, Gitelman's aminoglycosides syndrome Very low Mg2 diet Bartter's Mg malabsorption syndrome Drugs e.g., cisplatin, Gitelman's aminoglycosides syndrome Figure 10. Differential...

Intravenous Pyelography IVP

Radiologic techniques are based on the differential attenuation of X-rays by tissues. Dense structures such as bones greatly attenuate the beam and appear light on film. Low-density tissues like fat cause little attenuation and appear dark. High-osmolality contrast media diatrizoic or iothalamic acid are composed of a negatively-charged anion containing a benzene ring with 3 iodine molecules and a positively-charged cation sodium or methylglucamine . Newer low-osmolality agents, anionic...

Indications for Renal Biopsy

The most common settings for considering renal biopsy are the evaluation of the neph- rotic syndrome or nephrotic range prote-inuria, acute nephritis, and acute renal failure of obscure origin. Biopsies are also commonly done to evaluate renal dysfunction in transplanted kidneys. Less commonly, a biopsy may be undertaken in the evaluation on non-nephrotic range proteinuria and isolated hematuria. It is important to emphasize that the decision to pursue an invasive diagnostic study such as a...

Disorders with Hypokalemia and a Normal or High ECF Volume

Treatment For Hyperkalemia

- Pathophysiology Hypersecretion of al-dosterone due to an adrenal adenoma or bilateral adrenal hyperplasia. - Clinical Picture This diagnosis should be suspected in patients with hypertension and unexplained hypokalemia with renal K wasting. Nevertheless, hy-pokalemia is not a universal finding in these patients 69 . - Diagnosis requirement The diagnosis hinges on the finding of an elevated plasma aldosterone level and a very low plasma renin activity. A random plasma al-dosterone to plasma...

Biopsy Techniques Patient Selection and Tissue Handling

The most widely used biopsy method is the percutaneous renal biopsy. Most clinicians now favor localization of the kidney with ultrasound techniques because it provides more accurate localization than IVP and obviates the need for radiocontrast material. Additionally it is now possible, and some would argue desirable, to perform the procedure with real time ultrasound monitoring. Smaller bore needles 18-gauge spring-loaded devices instead of 14-gauge needles are increasingly popular because of...