Uremia - A Detailed Study

What Is Uremia?

Uremia is the term used to describe the accumulation of waste products in the blood. It is one of the typical signs of end-stage renal disease and acute kidney injury. Manifests as the fluid, electrolyte, metabolic and hormonal abnormalities due to poor kidney function.

What Is the Epidemiology of Uremia?

Uremia is the classic sign of renal failure; the incidence of patients developing renal failure represents the incidence of uremia. It is reported that 354 out of 1 million population develop end-stage renal disease. It is more common in men than women and is reported to be high in individuals above 75 years of age. Caucasians are the most affected race, followed by African Americans and Asian populations.

What Is the Etiology of Uremia?

The etiology can be categorized into two types:

• Primary causes.

• Secondary causes.

Primary Causes

Primary causes include the disease conditions primarily affecting the kidneys or causes within the kidneys like:

• Membranoproliferative Glomerulonephritis - It is caused due to the deposition of antibodies in the glomerular basement membrane of the kidneys.

• IgA Nephropathy - It is characterized by the deposition of IgA antibodies in the renal structures.

• Polycystic Kidney Disease - It is characterized by the formation of multiple cysts in the kidneys, thereby affecting kidney function.

• Focal Segmental Glomerulosclerosis - It is described as the formation of scar tissue in some parts of the glomeruli.

• Azotemia - It is the build-up of nitrogenous waste products such as blood urea nitrogen and creatinine in the blood.

Secondary Causes

Secondary causes include uremia caused by systemic factors such as:

• Uncontrolled Diabetes mellitus - May progress to end-stage renal disease due to chronic damage to the kidneys.

• Hypertension - Chronic uncontrolled hypertension will result in kidney injury and subsequent renal failure.

• Multiple Myeloma - This is a type of plasma cell cancer that causes inflammation of the kidneys leading to a condition called myeloma kidneys. In 20% of cases, it leads to kidney failure.

• Amyloidosis - This is the deposition of eosinophilic hyaline material affecting the kidneys, mainly leading to kidney damage.

• Goodpasture Syndrome - This is an autoimmune disorder affecting the lungs and the kidneys, one of the main causes of kidney failure.

• Hemolytic Uremic Syndrome - It is the formation of clots in the renal blood vessels causing damage to the filtering units of the kidneys.

What Is the Pathogenesis of Uremia?

Improper kidney function due to the above said etiologies would affect the fluid and electrolyte balance, acid-base balance, hormone secretion, and elimination of waste products. The collection of these waste products, as well as disturbed homeostasis mechanisms, would result in the development of other conditions such as,

• Anemia - Erythropoietin hormone is produced by the interstitial cells of the kidneys, but the damaged kidneys would fail to function, leading to anemia as a result of decreased red cell production.

• Bleeding Diathesis - The accumulation of waste products would eventually affect the platelet adhesion mechanisms and increase the risk of bleeding and hemorrhage.

• Acidosis - This would develop as the kidneys fail to maintain the acid-base balance, and build-up of organic acids in the blood with reduced excretion of hydrogen ions. This ends up in metabolic acidosis.

• Hyperkalemia - Is the increase in serum potassium levels greater than 6.5mEq/L.

• Hypocalcemia - This may occur as a result of decreased synthesis of the active form of Vitamin D.

• Hyperphosphatemia - This is the increase in serum phosphate levels due to decreased excretion from the kidneys.

• Hyperparathyroidism - This would result from hypocalcemia and hyperphosphatemia, which in turn stimulates the parathyroid gland leading to hyperparathyroidism.

• Pericardial Effusion - This may occur as a result of accumulated uremic toxins around the pericardium of the heart impairing cardiac functions.

• Subdural Hematoma - May develop in patients with high levels of serum blood urea nitrogen levels greater than 150mg/dl.

• Uremic Fetor - This is caused due to the excess urea in the blood reaching saliva, which then breaks down into ammonia, causing an ammonia odor from the mouth.

• Xerostomia - Is the dry mouth caused due to decreased salivary flow and reduced fluid intake.

What Are the Symptoms of Uremia?

The symptoms of uremia are caused by various pathologies, and the symptoms start to appear when the serum creatinine clearance falls below 10 ml/min. The symptoms are:

• Fatigue.

• Lethargy.

• Anorexia (fear of gaining weight).

• Weight loss.

• Nausea.

• Vomiting.

• Itching or pruritus.

• Loss of appetite.

• Confusion.

• Muscle cramps.

• Shallow respiration.

• Headache.

• Insomnia.

• Seizures.

• Anemia.

• Platelet dysfunction.

• Infertility in males.

• Amenorrhea in females.

• Bone diseases.

• Xerostomia (dry mouth).

How Is Uremia Diagnosed?

The steps in diagnosis include:

1. Medical History: Collecting history from the patient regarding the symptoms of the disease would definitely help in diagnosing the disease clinically. History regarding the underlying systemic diseases and the medications taken by the patients would assist in diagnosis and treatment planning.

2. Clinical Examination: A thorough clinical examination of the patient to check for signs of anemia, uremic breath, respiratory rate, and blood pressure levels is important to understand the progression of the disease.

3. Blood Examination:

• Serum Creatinine - An increase in serum creatinine levels would be evident as a result of functional failure of the kidneys

• Serum Urea - An increase in serum urea (uremia) levels would be evident.

• Blood Urea Nitrogen (BUN) Levels - Elevated BUN levels will be evident.

• Serum Calcium - Decreased serum calcium levels (hypocalcemia).

• Serum Phosphate - Increased serum phosphate levels (hyperphosphatemia).

• Serum Potassium - Increased serum potassium levels (hyperkalemia).

• Parathyroid Levels - This indicates hyperparathyroidism.

• Hemoglobin Estimation - This would indicate anemia (decreased red blood cell count).

• Glomerular Filtration Rate - This would be less than 30 ml/min indicating severe kidney disease; in patients with complete renal shutdown or failure, it would be less than 15 ml/min.

• Bleeding Time Estimation - This would indicate prolonged bleeding time.

4. Urine Analysis

• Creatinine Clearance - A 24-hour urine test would reveal a decreased creatinine clearance of less than 10ml/min.

• Microscopic Examination - This reveals the presence of urinary casts.

5. Renal Ultrasound: Is done to check for the size as well as the presence of any obstruction in the kidneys. Usually, the kidneys shrink in size as they lose their function; secondary causes such as multiple myeloma, glomerulonephritis, etc., may cause the kidneys to enlarge in size. Kidney stones and other causes causing obstruction could be visualized in the renal ultrasound.

6. Computed Tomography (CT) Scan: Is indicated in patients with the risk of subdural hematoma to provide a detailed report of the kidney’s structure, size, and the presence of any obstruction.

7. Magnetic Resonance Imaging (MRI) Scans: Are indicated to look for any damage in the renal arteries or renal artery thrombosis.

8. Microscopic Examination: This may not help in diagnosing the disease but provides an idea about the extent of damage to the kidneys and evaluates the prognosis of the condition.

How Is Uremia Managed?

By the time uremia develops, it indicates that the kidneys are severely damaged, and the treatment is aimed at removing the waste products from the blood. The treatment options include:

• Hemodialysis - It uses a machine to segregate waste products and fluids from the blood.

• Peritoneal Dialysis - A small catheter is inserted into the abdomen in the peritoneal membrane, and the waste products and fluids are collected and drained out of the body.

• Renal Transplantation - Transplantation of the kidneys gives better results than the other treatments. It should be considered based on the factors such as age, pre-existing conditions, and complications.

• Iron Replacement Therapy and Blood Transfusion - Are indicated in patients with anemia.

• Calcium Supplements - Are given to treat hypocalcemia.

• Vitamin D Supplements - To treat vitamin D deficiency.

• Dietary Recommendations - Patients are advised to take diets with low potassium, sodium, and phosphates. Diets rich in protein can be given, and the amount of fluid intake should be restricted.

• Avoid - Medications that are injurious to the kidneys should be avoided, such as NSAIDs and Aminoglycoside antibiotics.

What Is the Prognosis of Uremia?

The prognosis of patients developing uremia with renal failure is reported to be fair with proper treatment and care. But the mortality rate is high in patients with this condition as compared to the general population. Without treatment, the patients may die due to disarranged homeostasis and organ failure.

Conclusion

Uremia is a serious condition that develops in patients with end-stage renal disease. The symptoms develop as a manifestation of the accumulated waste products. The patients should receive immediate treatment to improve their survival. Untreated cases show poor prognosis; the patient may die due to the nonfunctional kidneys and the associated complications.