Question

Integrative Urinary Case Study

While working as a general practitioner, your patient Lamar comes to your office for a standard checkup. Because Lamar is 60 years old and has type II diabetes, you frequently subject him to lab tests to evaluate kidney function, as you know that kidney function can be compromised in diabetics.

Urinary Case Study.01

One type of damage that you are worried about detecting is damage to the endothelial cells of the kidney glomeruli and the podocytes that make up the Bowman’s capsule epithelium. This damage can cause the openings in these tissue layers (e.g., intercellular clefts and other fenestrations) to widen in diabetic patients. Based on analysis of a urine sample from Lamar (urinalysis), which of the following would be the best evidence that such damage has occurred?

A Higher than normal protein levels in the urine.

B Higher than normal Na levels in the urine.

C Lower than normal protein levels in the urine.

D Lower than normal Na levels in the urine.

Urinary Case Study.02

Unfortunately, you detect the evidence of kidney damage that you identified in question #1 from Lamar’s urinalysis results. What effect, if any, do you predict this will have on the osmotic pressure (osmolarity) of his blood plasma?

A It should be higher than normal.

B It should be normal.

C It should be lower than normal.

Urinary Case Study.03

Given the answer to question #2, what should happen to Lamar’s interstitial fluid volume?

A It should be higher than normal.

B It should be normal.

C It should be lower than normal.

Urinary Case Study.04

Why does the answer to question #2 cause the answer to question #3?

A Because Lamar’s TPR is higher than that of a healthy individual.

B Since the osmotic pressure of Lamar’s blood plasma should be the same as that of a healthy individual, it makes sense that his interstitial fluid volume should be normal.

C Because Lamar’s GFR is higher than that of a healthy individual.

D Because the balance of Starling’s forces in Lamar’s systemic capillaries is altered relative to that of a healthy individual.

Urinary Case Study.05

You also detect significant amounts of glucose in Lamar’s urine sample, which is typical in diabetics. What does this tell you about his kidney function?

A His glucose reabsorption rate must exceed his glucose excretion rate.

B His glucose reabsorption rate must exceed his glucose secretion rate.

C His glucose filtration rate must exceed his glucose secretion rate.

D His glucose filtration rate must exceed his glucose reabsorption rate.

Urinary Case Study.06

Since Lamar’s diabetes is very poorly controlled, you decide that you want to prescribe him another anti-diabetic drug in addition to the ones he is already on: a glifozin, which is a class of drugs that inhibit SGLTs (sodium-dependent glucose transporters). These drugs reduce blood sugar through their actions on the urinary system. Why would inhibiting SGLTs reduce blood sugar?

A Inhibiting SGLTs will increase the rate that glucose is reabsorbed by secondary active transport.

B Inhibiting SGLTs will reduce the rate that glucose is reabsorbed by secondary active transport.

C Inhibiting SGLTs will increase the rate that glucose is reabsorbed by primary active transport.

D Inhibiting SGLTs will decrease the rate that glucose is reabsorbed by primary active transport.

Urinary Case Study.07

Before he leaves, you measure Lamar’s blood pressure and find that it is elevated, as it has been over the past few visits. To attempt to get his hypertension under control you decide to prescribe him an ACE inhibitor. How will this drug lower his blood pressure?

A It will cause vasoconstriction of the afferent arterioles feeding the kidney glomeruli.

B It will enhance the activity of Na-K-ATPases in the basolateral membranes of proximal convoluted tubule epithelial cells (causing reabsorption of more Na per unit time).

C It will cause vasodilation of the efferent arterioles exiting the kidney glomeruli.

D It will increase rates of Na and HO excretion via the urine.

Answer 1

Urinary case study 1:

B. Higher than normal sodium levels in the urine.

Urinary case study 2:

C. It should be lower than normal.

Urinary case study 3:

A. It should be higher than normal.

Urinary case study 4:

B. Since the osmotic pressure of Lamar's blood plasma should be the same as that of a healthy individual , it makes sense that his interstitial fluid volume should be normal.

Urinary case study 5:

B. His glucose reabsorption rate must exceed his glucose secretion rate.

Urinary case study 6:

B. Inhibiting SGLTS will reduce the rate that glucose is reabsorbed by secondary active transport.

Urinary case study 7:

C.It will cause vasodilation of the efferent arterioles exiting the kidney glomeruli.