(USMLE topics) Uremia: Pathophysiology, Symptoms, Diagnosis and Treatment. This video is available for instant download licensing here: https://www.alilamedicalmedia.com/-/galleries/all-animations/urinary-system-videos/-/medias/f145e9f6-62e2-4e5f-80d3-99ea13b71af1-uremia-narrated-animation
Voice by: Ashley Fleming
©Alila Medical Media. All rights reserved.
Support us on Patreon and get early access to videos and free image downloads: patreon.com/AlilaMedicalMedia
All images/videos by Alila Medical Media are for information purposes ONLY and are NOT intended to replace professional medical advice, diagnosis or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.
Uremia, meaning urine in the blood, is the clinical syndrome associated with kidney failure. Most commonly, uremia develops gradually in the setting of chronic kidney disease, especially at later stages, but it may also occur with acute kidney injury.
Renal function is evaluated based on glomerular filtration rate, GFR, an indicator of how well the blood is filtered by the kidneys. GFR is calculated as a function of serum creatinine, a waste product that accumulates in blood plasma when renal function declines. Another parameter is creatinine clearance, the volume of blood plasma cleared of creatinine per minute.
When kidney failure develops gradually, symptoms usually occur when creatinine clearance drops below 10 mL/min. Typical symptoms include nausea, vomiting, fatigue, loss of appetite, weight loss, muscle cramps, itchy skin, and altered mental status.
Because the kidneys remove metabolic wastes, control blood pH and fluid/electrolyte balance, as well as produce several hormones, loss of renal function may result in a number of complications:
- Accumulation of toxic nitrogenous wastes can cause a range of symptoms, from nausea, vomiting to confusion and seizures. The buildup of uremic toxins may trigger inflammatory response of the pericardium, leading to uremic pericarditis and impaired cardiac function. Uremic toxins are also known to reduce platelet adhesion and increase platelet turnover, thereby causing bleeding disorders.
- Reduced insulin clearance can lead to increased episodes of hypoglycemia in diabetic patients.
- Decreased medication clearance may cause overdose and increased drug sensitivity.
- Reduced excretion of hydrogen ions leads to increased blood acidity, or metabolic acidosis.
- Decreased excretion of potassium results in potassium overload in the blood, or hyperkalemia, which may cause cardiac arrhythmias.
- Lower excretion of phosphate results in hyperphosphatemia.
- Reduced renal production of active vitamin D contributes to low blood calcium level, or hypocalcemia. Low blood calcium stimulates production of parathyroid hormone, PTH, by the parathyroid gland. PTH promotes calcium release from bones to raise blood calcium. This sequence eventually leads to an overactive parathyroid gland. As the bones continuously lose calcium to the blood, they become thin and weakened, a condition known as renal osteodystrophy.
- Reduced renal secretion of erythropoietin, a stimulating factor for red blood cell formation, can lead to anemia.
Diagnosis is based on clinical presentation and an abnormal GFR or creatinine clearance. Ultrasound is performed to detect renal obstruction and to differentiate between chronic and acute causes. Acute kidney failure can be reversed with treatment of the underlying condition.
Uremia is treated with renal replacement therapy, which can be accomplished by hemodialysis, peritoneal dialysis, or kidney transplantation.