Gout and Kidney Disorders Quiz

Kidney Function Tests

• Kidney function tests assess kidney function using blood urea nitrogen (BUN), serum creatinine, and glomerular filtration rate (GFR).
• Uremia is abnormally high blood urea nitrogen.
• Azotemia is an elevated plasma concentration of urea and creatinine in renal insufficiency.
• Prerenal, renal (intrinsic), and postrenal causes of elevated BUN/creatinine differentiate pathophysiologic processes.
• Calculating creatinine clearance estimates glomerular filtration rate (GFR).
• Factors affecting plasma creatinine levels include muscle mass, certain drugs, age, and sex.
• GFR is the volume of filtrate made per unit time by nephrons in both kidneys.
• Substances used to measure GFR are inulin, creatinine, and cystatin C.

Acute Renal Failure (ARF)

• ARF is an abrupt decline in renal function, manifesting as low GFR and increased BUN/creatinine levels.
• Classification includes pre-renal, renal, and post-renal causes.
• Pre-renal ARF is caused by reduced blood supply to the kidneys (e.g., hemorrhage, dehydration).
• Renal ARF is due to intrinsic kidney damage (e.g., glomerulonephritis, toxins, myoglobinuria).
• Postrenal ARF is caused by obstruction in urine outflow (e.g., stones, prostate issues).

Urea

• Urea is the main nitrogenous waste product of protein catabolism.
• Urea is produced in the liver and primarily excreted via kidneys.

Creatinine

• Creatinine is a breakdown product of phosphocreatine in muscle tissue.
• Measured in serum to assess renal function.
• Serum creatinine levels are slightly higher in males due to muscle mass.

Glomerular Filtration Rate (GFR)

• GFR is the volume of filtrate formed by all nephrons per unit of time.
• Measuring GFR helps detect and diagnose renal insufficiency.
• GFR is used to adjust drug dosages in patients with kidney problems.
• Inulin, cystatin C, and creatinine are used to measure GFR.

Causes of High BUN (Uremia)

• Prerenal uremia: reduced blood flow to the kidney
• Renal uremia: intrinsic kidney disease (acute/chronic glomerulonephritis, polycystic kidney disease)
• Postrenal uremia: obstruction in urine outflow (stones, prostate enlargement, malignancy)

Proteinuria

• Proteinuria is the presence of abnormal amounts of protein in urine.
• Types of proteinuria include glomerular, overflow, and tubular.
• Glomerular proteinuria results from damage to the glomeruli.
• Overflow proteinuria may be caused by elevated low-molecular-weight proteins in the blood (e.g., hemoglobin, myoglobin).
• Tubular proteinuria is from decreased reabsorption capacity of proteins in the tubules

Uric Acid and Gout

• Uric acid is produced from purine metabolism.
• A high level, hyperuricemia, can cause gout.
• Gout causes inflammation in joints.
• Primary Gout is often familial.
• Secondary Gout can be due to increased production or decreased excretion of uric acid.

Clinical Significance of Serum Creatinine

• Creatinine is freely filtered by glomeruli, with minimal tubular secretion.
• Elevated serum creatinine suggests decreased renal excretion, often a sign of renal dysfunction.
• Serum creatinine levels are somewhat higher in males and affected by age, sex, muscle mass, certain drugs, exercise, and high protein diets/ catabolic states.

Creatinine Clearance

• Creatinine clearance is the volume of plasma cleared of creatinine by the kidneys per minute.
• Calculating creatinine clearance helps assess kidney function.

Microalbuminuria

• Microalbuminuria is a small amount of albumin in urine.
• It's an early sign of kidney disease, especially in patients with diabetes and hypertension.

Case Scenario

• The case scenario presents a patient with possible acute kidney injury (AKI) due to decreased renal function.
• Reduced renal function (low GFR) and abnormal blood chemistry data may indicate heart failure.

Summary of Kidney Lecture

• The lecture covers laboratory assessments of renal function, focusing on key kidney health/disease indicators (BUN, creatinine, etc).
• Specific tests for renal function include blood urea and blood urea nitrogen (BUN), Uremia, Azotemia , and Creatinine, GFR.