Nephrology

The Néphrologie is the medical speciality aiming to prevent, diagnose and to look after the diseases of the Rein S. It is different from the Urologie, speciality surgical being interested in the genital apparatus male and the unit of the urinary Système (Rein S, Uretère S, Vessie, Prostate, Urètre).

The word nephrology comes from the Greek words nephros (kidney) and logos (study). Very many diseases affecting the kidneys are not limited to this body but are general Maladies (Athérosclérose, diabetes, etc).

Renal physiology

The Rein S have a double function, excrétrice and hormonal.

Function excrétrice

It consists of the formation of the Urine, by which the products are eliminated from the Catabolisme.
the functional unit of the kidney is the néphron, composed of a cluster, a tubule, a related small artery (which enter the cluster) and of an efferent small artery (which in fate).

The primitive urine is obtained in the cluster by passive Ultrafiltration of the plasma through the surface of filtration (constituted by the superposition of the capillary endothelium and the visceral layer of the capsule of Bowman), under the action of the gradient of pressure existing between the related small artery, where reign blood pressure, and the glomerular room (also called space of Bowman ), in which reign pressure of the way higher excrétrice (normally weak). The ultrafiltrat thus obtained runs out towards the tubule.

The glomerular rate of Filtration is about 120 ml/min, which means that each day, approximately 180 liters of ultrafiltrat plasmatic are produced in the clusters and are transported in the tubules. This primitive urine is reabsorbed to 99% at the time of its passage in the successive tubular segments which it crosses (tube circumvented proximal, handle of Henlé then distal tube), where the various mechanisms of secretion and reabsorption occur which lead to the development from approximately 1,5 liter of final Urine per day.

The ionic movements transtubulaires of Secretion and reabsorption of the substances contained in the urine are either passive (electrochemical gradient), or credits and consuming energy. These exchanges of water, urea, electrolytes, etc between the tubule and blood are done with the efferent small artery which, after its exit of the cluster, remains close to the tubules.

Hormonal function

  • Secretion of the érythropoïétine, hormone stimulating the érythropoïèse
  • Secretion of the Renin, hormone intervening in the regulation of the Pressure blood and in the metabolism of the Sodium and the Potassium via the Angiotensin and of the Aldosterone
  • Hydroxylation of the Vitamin D, inactive, in a hydroxylated derivative in position 1 (after a first hydroxylation into 25 by the Liver, leading to the dihydroxylé active derivative of the Vitamin D, the 1-25 dihydroxycholécalciférol which plays an important role in the Métabolisme phosphocalcic and osseous.

Symptoms nephrologic

The patients can have to be dealt with by nephrologist for Symptôme S varied such as:
  • a Anurie
  • a Oliguria
  • a Polyurie
  • of the edema S
  • a Protéinurie (often improperly called “albuminuria”): presence of Protein S in the Urine S. When this protéinurie is very abundant, causing a notable reduction in the blood rates of Protides and Albumine, it can carry out a nephrotic Syndrome, which is always caused by a glomerular Néphropathie
  • a Hématurie: presence of Blood in the Urine S, either visible (hématurie macroscopic), or invisible (hématurie microscopic)
  • a arterial Hypertension
  • a Impaired renal function: deterioration of the renal Function defined by a reduction in the glomerular rate of Filtration; it is characterized biologically by disturbances of the blood composition: abnormally high rates of the Urea and especially of the blood Creatinin, with reduction in the clearance of creatinin. It can be a question of a acute Impaired renal function or a chronic Impaired renal function
  • a acute syndrome nephritic, defined by the brutal appearance of edema S, a arterial Hypertension, a often macroscopic Hématurie, of a Protéinurie and sometimes of a acute Impaired renal function. This syndrome is always caused by a glomerular Néphropathie proliferative.
  • a renal colics: force painful crisis caused by the setting in tension of the secondary renal capsule to an obstacle with the flow of the urines (Lithiase urinary or different)
  • of the urinary infections with hydroelectrolytic repetition
  • of the disorders relating to for example the Natrémie, the Kaliémie or the Calcémie

Diagnostic methods in nephrology

As always in medicine, of the important indications are provided by the collection and the data analysis of the Interrogatoire and the Clinical examination.

The tests of laboratory generally employed in nephrology are blood and urinary examinations:

The other examinations often necessary to the nephrologist concern the Medical imagery and the Anatomo-pathology:

  • the echography of the Kidney S and the urinary tracts (Uretère S, Bladder, Prostate).

  • the scanner (also called tomodensitométre) of the Kidney S and the Abdomen.
  • the renal Scintiscanning (examination of Nuclear medicine).
  • the Angiographie allowing to explore the vessels.
  • the renal Biopsy: taking away of a renal fabric fragment whose analysis with the Microscope makes it possible to diagnose the type of the renal disease in question and to appreciate gravity of it.

Nephrologic affections

The prevalence of the chronic renal diseases would reach 10 to 15% of the adult American population. It would be in slight increase, partly due to the increase in the frequency of the arterial Hypertension and the Diabète.

Nephropathies

Glomerular nephropathies

Primitive glomerular nephropathies
  • lipoidic Néphrose (also called nephrotic syndrome idiopathic, in particular in the segmentary child
  • Hyalinose and focal distance
  • extra-membranous Glomerulonephritis
  • Disease of Shepherd or glomerulonephritis with mésangiaux deposits of IgA
  • membrano-proliferative Glomerulonephritis
  • Glomerulonephritis extra-capillary
  • gravidic Nephropathy

Secondary glomerular nephropathies
A glomerulonephritis can occur during the evolution of some general diseases:

Tubular and interstitial nephropathies

  • Necroses tubular or acute tubulo-interstitial nephropathy
  • chronic Tubulopathie
  • chronic tubulo-interstitial Néphropathies
  • chronic Pyélonéphrite

Vascular nephropathies

Congenital nephropathies

  • Polykystose renal
  • Syndrome of Alport
  • Néphronophtise

Impaired renal function

Other nephrologic affections

Affections of vascular origin

  • vasculo-renal arterial Hypertension

Affections of urologic origin

Hydro-electrolytic disorders

Treatment

Certain renal diseases are treated by Médicament S such as the Corticoïde S or the Immunosuppresseur S. Beaucoup of patients require a treatment by drugs Diurétique S or Antihypertenseur S (because the majority of the renal diseases are accompanied by a arterial Hypertension).

The chronic Impaired renal function is usually accompanied by a reduction in the synthesis of two Hormone S, the érythropoïétine (Epo) and the Vitamine D, which requires a substitute treatment. When the chronic Impaired renal function reaches the stage of final Impaired renal function, the survival of the patients rests on the substitute treatment by Dialyze or renal transplantation.

External bond

Famous nephrologists

See too

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