Urinary System Flashcards
after 2 days in the hospital, Mr. Boulard has recovered from his acute diabetic crisis and his type 1 diabetes is once again under control. The last update on his chart before discharge includes the following:
-BP 150/95,HR75, temperature 37.2*C
-Urine:pH 6.9, negative for glucose and ketones; 24 hour urine collection reveals 170mg albumin in urine per day
Mr Boulard is prescribed a thiazide diuretic and an angiotensin converting enzyme (ACE) inhibitor. He is counseled on the importance of keeping his diabetes under control, taking his medications regularly, and keeping his outpatient follow up appointments
.
What is albumin? Is it normally found in the urine? If not, what does its presence suggest?
Albumin is the smallest and most abundant plasma protein. More than trace amounts of albumin are not normally found in urine, so its presence indicates damage to the filtration membrane of the nephron.
Why were these medications prescribed for Mr. Boulard?
these medications were prescribed to treat Mr. Boulard’s hypertension. Both diabetes and hypertension can cause kidney damage, and hypertension is a major cause of other cardiovascular diseases such as heart failure and stroke. Albuminuria indicates that Mr. Boulard already has damage to his kidneys, so it is important to protect his kidneys, from further damage.
Where and how do thiazide diuretics act in the kidneys and how does this reduce blood pressure?
Thiazide diuretics increase urine output by inhibiting Na+ reabsorptions in the DCT. This decreases blood volume, which decreases blood pressure
At his 2 week appointment at the outpatient clinic, Mr. boulard complains of fatigue, weakness, muscle cramps, and irregular heartbeats. A physical examination and lab tests produce the following observations:
- BP 133/90, HR 75
- Blood K+ 2.9mEq/L (normal 3.5-5.5 mEq/L); blood NA+ 135mEq/L ( normal 135-145 mEq/L)
- Urine K+ 55mEq/L ( normal 20mEq/L)
.
What is Mr. Boulard’s main problem at this point?
While Mr. Boulard still has hypertension, his main problem is that his blood K+ is low. He is losing too much K+ in his urine. This is the underlying cause of his irregular heartbeat, which could turn into a fatal arythmia if his hypokalemia is not corrected.
Explain how the thiazide diuretic might have caused this problem?
Thiazide diuretics increase Na+ excretion and decrease blood pressure. To compensate for these thiazide effects, Mr Boulard’s renin-agiotensin-adolsterone mechanism is activated. Adolsterone increases Na+ reabsorption and K+ secretion, resulting in hypokalemia (low blood K+)
When asked about his medications, Mr. Boulard admits that he did not fill his ACE inhibitor prescription because it was too expensive. He can only afford the thiazide medications along with his insulin.
How do the ACE inhibitors reduce blood pressure?
ACE inhibitors decrease blood pressure by blocking the action of angiotensin converting enzyme and so reducing the amount of angiotensin II. Because angiotensin II increases blood pressure in a number of ways, including by increasing aldosterone release and causing vasoconstriction, ACE inhibitors are very effective at loweing blood pressure. (ACE inhibitors also help minimize kidney damage in diabetes)
Would taking ACE inhibitors and thiazides together have prevented Mr. Boulard’s current symptoms? Explain.
Yes. The ACE inhibitors would have prevented the formation of excess angiotensin II and the resulting release of aldosterone. This would have lessoned excess secretion of K+.
