4.3 PROTEIN Flashcards
What is the most indicative routine chemical test for renal disease?
Protein determination in urine.
What is the normal amount of protein excreted in urine daily?
Less than 10 mg/dL or 100 mg/24 hours.
What is the major serum protein found in normal urine?
Albumin.
At what concentration does clinical proteinuria begin?
30 mg/dL (300 mg/L) or greater.
What are the three major categories of proteinuria based on origin?
Prerenal, Renal, and Postrenal.
What causes prerenal proteinuria?
Increased low-molecular-weight plasma proteins due to conditions like infections and inflammation.
What is a primary example of prerenal proteinuria involving multiple myeloma?
Bence Jones protein.
What causes renal proteinuria?
Glomerular membrane damage or tubular dysfunction.
How does glomerular damage cause proteinuria?
It impairs selective filtration, allowing serum proteins, red blood cells, and white blood cells to pass through the glomerulus.
What benign conditions can cause transient renal proteinuria?
Strenuous exercise, fever, dehydration, and exposure to cold.
What condition can be predicted by the detection of microalbuminuria?
Diabetic nephropathy.
What is the albumin range for microalbuminuria?
20 to 200 mg/L.
A benign proteinuria occurring after being in a vertical position, disappearing when lying down.
orthostatic proteinuria
How can orthostatic proteinuria be diagnosed?
Negative protein test in the first morning specimen and positive test after standing for several hours.
What conditions cause tubular proteinuria?
Disorders like Fanconi syndrome, exposure to toxins, heavy metals, or viral infections.
What is postrenal proteinuria caused by?
Infections, inflammations, or contamination with blood, prostatic fluid, or sperm from the lower urinary tract.
What are the components of normal urine protein?
Low-molecular-weight serum proteins,
albumin,
tubular microglobulins,
uromodulin (Tamm-Horsfall protein), and
genitourinary proteins.
A glycoprotein produced by the renal tubular epithelial cells in the ascending loop of Henle.
uromodulin
What is uromodulin, and where is it produced?
A glycoprotein produced by the renal tubular epithelial cells in the ascending loop of Henle.
is a low-molecular-weight immunoglobulin light chain found in urine due to multiple myeloma, which overwhelms the renal reabsorptive capacity.
Bence Jones protein
What are major causes of glomerular proteinuria?
Amyloid deposits, immune complexes (e.g., in lupus, glomerulonephritis), toxic substances, and increased glomerular pressure.
What is the characteristic feature of Bence Jones protein in a heat-based screening test?
Bence Jones protein coagulates between 40°C and 60°C and dissolves at 100°C.
How is interference from other proteins removed in the Bence Jones protein test?
By filtering the specimen at 100°C, then observing for turbidity as it cools to between 40°C and 60°C.
How was microalbuminuria detected before modern reagent strip methods?
By collecting a 24-hour urine specimen and using quantitative procedures to measure albumin levels, reported in mg/24 hours or as the albumin excretion rate (AER).
