This document provides an overview of nephrology and kidney function. It discusses the anatomy of the kidneys and nephrons, as well as the physiology of glomerular filtration and tubular function. It also outlines several main kidney syndromes including nephritic syndrome, nephrotic syndrome, acute renal failure, and chronic kidney disease. Finally, it describes various exams that are used to evaluate kidney function such as urine analysis, blood tests, renal functional tests, imaging techniques, isotopic explorations, and kidney biopsy.

1. UNIVERSIDAD TECNICA DE MACHALA
ACADEMIC UNIT OF CHEMICAL
SCIENCES AND HEALTH
MEDICINE SCHOOL
ENGLISH
GENERALITIES OF
NEPHROLOGY
STUDENTS
William Cruz
Kevin Herrera
Jorge Pacheco
Angie Chamba
Sonia Quijilema
TEACHER:
Mgs. Barreto Huilcapi Lina Maribel
CLASS:
EIGHTH SEMESTER ‘’A’’
Machala, El Oro
2018

2. GENERALITIES OF NEPHROLOGY
Anatomy.- conformed by the kidneys, where each one has about 1 million
nephrons, which constitute the functional unit. Several are the functions of the
kidney, among which the regulation of water, salt, potassium, calcium,
phosphorus and acid-base metabolism. By regulating salt and body waters, the
kidney is important in determining the osmolality of body fluids and blood
pressure. The elimination of toxic, endogenous or exogenous substances is
another of the important functions of the kidney. Finally, the production of
hormones, such as erythropoietin, components of the renin angiotensin
aldosterone system and vitamin D, dihydroxylated, are endocrine functions of the
kidney.
The nephrons are composed of an interface of vascular tissue and epithelial tissue,
which begins with the glomerulus. It distinguishes a capillary bed preceded by an
arteriole (afferent) and another aterole (efferent). A double-layer epithelial cell
surrounds the glomerular capillaries to generate the Bowman's capsule. The
visceral layer is composed of podocytes, which embrace the fenestrated capillaries
of the glomerulus to define the properties of the glomerular ultrafiltrate. The
epithelial layer forms the wall of the glomerulus, which separates the urinary
space from the renal interstitium. The rest of the nephron consists of the renal
tubules, which are divided into a proximal convoluted tubule, loop of Henle
(descending and ascending), distal convoluted tubule and connecting tubule.
Physiology.- Renal function depends on two fundamental processes: glomerular
filtration and tubular function. Glomerular filtration is a passive process that
depends on the anatomical integrity of the glomerulus and the renal perfusion
pressure. The tubular function, on the other hand, is a highly active process in
which 99% of the 180 L ultrafiltered plasma must be reabsorbed every 24 h. In
this way, the final urine is the combination of glomerular filtration, reabsorption
and tubular secretion.
Main Syndromes.- Among the main syndromes of the excretory system we have:

3. a) Isolated urinary disorders, proteinuria, hematuria and isolated
leukocyturia.
b) The nephritic syndrome, consists of the appearance of hematuria (macro or
microscopic) together with acute alterations of renal functionalism
(oliguria, nitrogen retention, decrease in glomerular filtration), edema
formation and arterial hypertension.
c) Nephrotic syndrome is defined as proteinuria greater than 3.5 g / 24 h,
accompanied by hypoalbuminemia, edema and hyperlipemia.
d) Acute renal failure, characterized by an acute or rapid deterioration of
glomerular filtration, the appearance of oliguria or anuria.
e) Chronic kidney disease, indicates that the glomerular filtrate is reduced or
that there is the presence of markers of renal damage such as albuminuria
or hematuria.
f) Isolated tubular defects, consists of a decrease in the capacity for the
transport of solutes (glycosuria, phosphaturia, aminoaciduria) or to
concentrate or acidify the urine (renal tubular acidosis).
g) High blood pressure is defined in the adult as the pressure of 140 mm Hg
over 90 mm Hg.
h) Urinary infection, the presence of urine culture with more than 100,000
CFU / mL of bacteria in the urine or the demonstration of other less
frequent germs (M. tuberculosis, C. albicans) by specific techniques. h)
Renal lithiasis, defined by the expulsion of one or several stones, nephrotic
colic does not constitute sufficient evidence.
i) Urinary obstruction, we speak of low urinary obstruction when the
emptying of the bladder is incomplete, and high urinary obstruction when
there is dilatation of the ureter or of the pelvis and renal calyces.
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Exams.- is complemented for an adequate diagnosis, among which we have:
 Urine analysis. The quickest and simplest test is the use of test strips that
estimate in a semiquantitative way the presence of proteins, ketone bodies,

4. leukocytes and hemoglobin. Proteinuria, it is estimated when protein is
higher than 300 mg / 24 h, we say it is pathological. Microalbuminuria, is
the permanent excretion of albumin amounts between 30 and 300 mg / 24
h is also pathological and is called microalbuminuria, and in amounts
greater than 300 mg / 24 h are called macroalbuminuria. Urinary sediment,
in a healthy individual the urine contains less than 3 red blood cells / field,
less than 5 leukocytes / field and some hyaline cylinders, epithelial cells
and crystals. Urine culture, the urine is collected in maximum asepsis in a
sterile container and the sample is taken during half-voiding, it is
pathological when the count is 100 000 CFU / mL of bacteria.
 Blood test. In this the metabolites in the proteins are valued. Urea, is the
main one, the concentration of urea in blood is between 10-40 mg / dL and
increases if renal function decreases. Creatinine is a product of muscle
metabolism of cretin and is almost exclusively eliminated by glomerular
filtration, its concentration in blood depends mainly on the muscle mass of
each individual and in adults the normal concentration is equal to or less
than 1.2 mg / dL in men and equal to or less than 1.0 mg / dL in women. In
addition, blood tests include hemoglobin, ionogram (Na, Cl, K), acid-base
balance (pH, pCO2, HCO3). calcium, phosphorus, uric acid and serum
albumin.
 Renal Functional Tests. Most tests designed to examine the renal
excretion capacity of a substance that is eliminated in the urine uses the
notion of renal clearance or clearance. To measure glomerular filtration,
the most used formula is that of Cockcroft-Gault, which we only add to the
equation the multiplication by 0.85 when referring to a woman:
 Image techniques. On abdominal x-ray, we can obtain information about
the situation, size and shape of the kidneys. The intravenous urography
allows to visualize the radiodense image of the renal parenchyma
(nephrogram), as well as the opaque mold of the collecting system
(pyelogram) and the rest of the urinary tract. The ultrasound allows to
study the kidneys and detect renal and pararenal masses, cystic formations
(polycystosis), dilation of the cavities (hydronephrosis) and alterations of

5. the renal echoestructure, as well as to evaluate the echogenicity, the
cortical thickness and the degree of corticomedullary differentiation and
guide the introduction of needles for renal biopsy. Computed tomography
helps us with the detection, delimitation and detoxification analysis of
renal masses. Magnetic resonance imaging precisely defines the intrarenal
architecture, although the appearance of the kidneys is different depending
on the specific MRI technique used. And, renal angiography, which helps
us visualize in detail the vascularization of the kidney.
 Isotopic explorations. Some intravenous radioisotopes are accumulated or
excreted by the kidney to provide useful information about the
morphology and function of the excretory system. The isotopic renogram,
which is a temporary record of the radioactivity accumulated in the kidney
after the injection of a renal elimination radiopharmaceutical such as
dimethylenetriamine or mercaptoacetyltriglycine labeled with an isotope
of technetium. Renal scintigraphy is used with renal elimination
radiopharmaceutical injection, which is visualized with a high resolution
gamma camera, the kidneys and the urinary tract. Renal angiography,
indicated when there is suspicion of an acute and recent occlusion of the
renal artery.
 Kidney biopsy. Indicated in diseases of renal parenchyma of diffuse
character, it does not constitute an initial exploration, but it is reserved for
those cases in which a definitive diagnosis can not be obtained with other
means.
BIBLIOGRAPHIC REFERENCE:
GAMBA, AYALA, G. Exploration and main syndromes of the excretory system.
In: ROZMAN and FARRERAS. Internal Medicine. Spain, Elseiver, 2016. pp
763-771