Azotemia – “Azot” means nitrogen and “emia” means blood condition which is characterized by an elevation of blood urea nitrogen (BUN) and creatinine levels and is largely due to decreased glomerular filtration rate.
It is typical feature of both acute and chronic kidney injury
It is divided into three types depending upon the etiology
Pre-renal Azotemia –
When there is hypo perfusion of the kidney (eg. Hypotension or excessive fluid loss or decrease in effective intravascular volume due to shock or congestive heart failure) that impairs renal function in the absence of parenchymal damage.
There is enhanced proximal tubular reabsorption of salt and water as well as Urea, BUN, calcium, uric acid, bicarbonate
Primary renal azotemia –
Renal azotemia is the result of kidney parenchymal damage which decreases glomerular filtration
Causes include kidney failure, glomerulonephritis, acute tubular necrosis or any other kind of kidney disease
Post renal azotemia
When urine flow is obstructed distal to kidney. Nephron tubular pressure is elevated due to fluid back up which causes increased reabsorption of urea, elevating it abnormally relative to creatinine
Uremia
Azotemia associated with clinical signs, symptoms and biochemical abnormalities is Uremia
Uremia is clinical syndrome characterised by failure of renal excretory function along with metabolic, endocrine alterations and fluid electrolyte imbalance resulting from renal damage
Uremic patients frequently manifest secondary involvement of
Gastrointestinal system – uremic gastroenteritis
Heart – Uremic fibrinous pericarditis
Neuromuscular – peripheral neuropathy, leg cramps
Endocrine abvnormality – Thyroid dysfunction and insulin resistance
Metabolic – Amenorrhea, sexual dysfunction, muscle wasting , hypothermia
Non- Specific – Itching, serositis.
References
Vinay kumar, Abul K.Abbas, Nelson Fausto, Jon C. Aster. The Kidney. In: Robbins and Cotran Pathologic basis of disease. 8th edition.
