Question on question & atta boy for tommy

[stimpy13]

Firstly ...way to go tommy i hope that someone as willing to teach as you blesses the remainder of my medical education.

ok i have been going through every question tommy has posted , tying them into my notes ,looking up what i don't know , making flash cards etc ...

ok Tommy wrote

A woman with sarcoidosis or with hypercalcemia (there are a thousand ways to ask this concept) enters your clinic, which is the diuretic of choice?

with the answer

Furosemide, NOT thiazides or mannitol, or acetazolamide

however

katzung basic and clinical pharm pg 254 says

heading
"F other toxicities"
text
"loop agents are know for their calciuric effect but hypercalcemia can occur.Hypercalcemia is most likely to occur in pts who become dehydrated or have another- previously occult-cause for hypercalcemia "

So asks the padawan is the teaching point here that loop diuretics are primarly calciuric ? In the case of pre existing hypercalcemia or a condition that might predispose a pt to hypercalcemia (sarcadosis or oat cell CA) are loop diuretics still the best chioce?

anyone ? bueller ?

and thanks again to tommy

later

andrew

[Anonymous]

Hi Stimpy. Since Bueller isn't answering, I'll give it a shot . First, please don't make the common mistake of mixing up the words calcemia (blood Ca) and calciuria (urine Ca). But I think your question is asking whether the SE of the diuretics applies to everyone, or just people predisposed to having Ca metabolism problems (correct me if I misunderstood). If that's the case than the answer is that it will cause the side effect regardless, but to varying degrees. Normally if Ca is altered in the blood, endocrine mechs will respond to balance this out to a certain extent. In people predisposed, the balance will be less effective because there is already a problem with their endocrine system. So adding the diuretic will simply add to that effect.

For USMLE purposes, know the side effect, but also know the dzs that are contraindicated. In the case that you mentioned, a pt with hypercalcemia should be given furosemide because it's a LOOp which LOOses calcium (from blood to urine). So it will decrease the blood calcium, but will increase the urine calcium (hypercalciuria).

A thiazide, on the other hand, will retain calcium in the blood (hypercalemia), so it will not dump any into the urine (hypocalciuria). This might be beneficial to prevent calcium stones, but contraindicated in a pt with hypercalcemia, since that is one of the side effects and would add to the condition.

Look at the recent diuretic question here for more info
http://www.valuemd.com/viewtopic.php?t=14044

Hope this helps.