Final answer:
The best initial test for a patient with proteinuria is a routine urinalysis, which examines various aspects of urine to assess kidney function and can detect the presence of proteins such as albumin or Bence Jones proteins under specific conditions.
Step-by-step explanation:
The best first test for a patient with proteinuria is a routine urinalysis. This test is simple, cost-effective, and can provide immediate information about kidney function. It examines the physical, chemical, and microscopic aspects of the urine. A more specific test for proteinuria is the detection of albumin, as it is the major protein that leaks into urine when there are issues with the glomerulus.
Sulphosalicylic acid test, Heller's test, and heat coagulation are used to detect presence of proteins such as albumin in the urine. In some cases, when diseases like multiple myeloma are suspected, Bence Jones proteinuria can be identified by heating the urine sample.