Re: Furosemide

[Guest guest]

Roni,

You wrote:

>

>

> My cardio wants me on furosemide. I take it in the morning with my

> Armour, and a bit later

> a potassium supplement.

>

> 1. Will the three things interract and how?

>

I doubt that these will interfere with absorption, but furosemide

definitely interferes with thyroid by inhibiting binding. It can

actually INCREASE your free T3/T4 fractions. That could be hazardous.

Here's an abstract:

Interaction of furosemide with serum thyroxine-binding sites: in vivo

and in vitro studies and comparison with other inhibitors., J Clin

Endocrinol Metab. 1985 May;60(5):1025-31. Stockigt JR, Lim CF, Barlow

JW, Wynne KN, Mohr VS, Topliss DJ, Hamblin PS, Sabto J.

The diuretic furosemide inhibits serum protein binding of T4 in

equilibrium dialysis, dextran-charcoal, and competitive ligand binding

separation systems and displaces [125I]T4 from isolated preparations of

T4-binding globulin (TBG), prealbumin, and albumin. Equilibrium dialysis

studies of undiluted normal serum showed that about 10 micrograms/ml

furosemide increased the free T4 and free T3 fractions. Displacement

occurred at lower drug concentrations in sera with subnormal albumin and

TBG levels. Binding of [14C]furosemide to TBG was inhibited by unlabeled

T4, suggesting that furosemide and T4 share a common binding site. A

single oral dose of 500 mg furosemide given to five patients maintained

on peritoneal dialysis increased the percentage of charcoal uptake of

[125I]T4 (using serum diluted 1:10) from 4.1 +/- 1.0 (+/- SE) to 10.8

+/- 4.3 (P less than 0.01) after 2 h, while decreasing total T3 from 75

+/- 5 to 56 +/- 13 ng/dl (P less than 0.01) and total T4 from 6.7 +/-

0.9 to 4.8 +/- 0.8 micrograms/dl (P less than 0.01) after 5 h. Various

ligands inhibited [125I]T4 binding to serum proteins in the following

relative molar relationship: T4, 1; furosemide, 1.5 X 10(3);

fenclofenac, 2 X 10(4); mefenamic acid. 2.5 X 10(4); diphenylhydantoin,

4 X 10[4); ethacrynic acid, 10(5); heparin 5 X 10(5);

2-hydroxybenzoylglycine, 10(6); and sodium salicylate, 1.5 X 10(6).

These studies demonstrate that furosemide competes for T4-binding sites

on TBG, prealbumin, and albumin, so that a single high dose can acutely

lower total T4 and T3 levels. The drug is much more potent on a molar

basis than other drug inhibitors of T4 binding, but at normal

therapeutic concentrations, furosemide is unlikely to decrease serum T4

or T3. However, high doses, diminished renal clearance, hypoalbuminemia,

and low TBG accentuate its T4- and T3-lowering effect. Hence, furosemide

should be considered a possible cause of low thyroid hormone levels in

patients with critical illness. The significance of this drug in reports

of impaired hormone and drug binding in renal failure requires further

assessment.

> 2. If this method is not good, what should I do instead?

>

Make sure your cardio knows you taking a thyroid med, or make sure your

thyroid doc knows about the furosemide. You may to adjust a dosage.

Chuck

[Guest guest]

Thank you for this information. Maybe that's why I've been having so many

symptoms in the last 4 months or so.

Roni

Chuck B <gumboyaya@...> wrote:

Roni,

You wrote:

>

>

> My cardio wants me on furosemide. I take it in the morning with my

> Armour, and a bit later

> a potassium supplement.

>

> 1. Will the three things interract and how?

>

I doubt that these will interfere with absorption, but furosemide

definitely interferes with thyroid by inhibiting binding. It can

actually INCREASE your free T3/T4 fractions. That could be hazardous.

Here's an abstract:

Interaction of furosemide with serum thyroxine-binding sites: in vivo

and in vitro studies and comparison with other inhibitors., J Clin

Endocrinol Metab. 1985 May;60(5):1025-31. Stockigt JR, Lim CF, Barlow

JW, Wynne KN, Mohr VS, Topliss DJ, Hamblin PS, Sabto J.

The diuretic furosemide inhibits serum protein binding of T4 in

equilibrium dialysis, dextran-charcoal, and competitive ligand binding

separation systems and displaces [125I]T4 from isolated preparations of

T4-binding globulin (TBG), prealbumin, and albumin. Equilibrium dialysis

studies of undiluted normal serum showed that about 10 micrograms/ml

furosemide increased the free T4 and free T3 fractions. Displacement

occurred at lower drug concentrations in sera with subnormal albumin and

TBG levels. Binding of [14C]furosemide to TBG was inhibited by unlabeled

T4, suggesting that furosemide and T4 share a common binding site. A

single oral dose of 500 mg furosemide given to five patients maintained

on peritoneal dialysis increased the percentage of charcoal uptake of

[125I]T4 (using serum diluted 1:10) from 4.1 +/- 1.0 (+/- SE) to 10.8

+/- 4.3 (P less than 0.01) after 2 h, while decreasing total T3 from 75

+/- 5 to 56 +/- 13 ng/dl (P less than 0.01) and total T4 from 6.7 +/-

0.9 to 4.8 +/- 0.8 micrograms/dl (P less than 0.01) after 5 h. Various

ligands inhibited [125I]T4 binding to serum proteins in the following

relative molar relationship: T4, 1; furosemide, 1.5 X 10(3);

fenclofenac, 2 X 10(4); mefenamic acid. 2.5 X 10(4); diphenylhydantoin,

4 X 10[4); ethacrynic acid, 10(5); heparin 5 X 10(5);

2-hydroxybenzoylglycine, 10(6); and sodium salicylate, 1.5 X 10(6).

These studies demonstrate that furosemide competes for T4-binding sites

on TBG, prealbumin, and albumin, so that a single high dose can acutely

lower total T4 and T3 levels. The drug is much more potent on a molar

basis than other drug inhibitors of T4 binding, but at normal

therapeutic concentrations, furosemide is unlikely to decrease serum T4

or T3. However, high doses, diminished renal clearance, hypoalbuminemia,

and low TBG accentuate its T4- and T3-lowering effect. Hence, furosemide

should be considered a possible cause of low thyroid hormone levels in

patients with critical illness. The significance of this drug in reports

of impaired hormone and drug binding in renal failure requires further

assessment.

> 2. If this method is not good, what should I do instead?

>

Make sure your cardio knows you taking a thyroid med, or make sure your

thyroid doc knows about the furosemide. You may to adjust a dosage.

Chuck

------------------------------------

[Guest guest]

I forgot to tell you that I am on a very small dose, only 20 mgs. Does that make

a difference?

Roni

Chuck B <gumboyaya@...> wrote:

Roni,

You wrote:

>

>

> My cardio wants me on furosemide. I take it in the morning with my

> Armour, and a bit later

> a potassium supplement.

>

> 1. Will the three things interract and how?

>

I doubt that these will interfere with absorption, but furosemide

definitely interferes with thyroid by inhibiting binding. It can

actually INCREASE your free T3/T4 fractions. That could be hazardous.

Here's an abstract:

Interaction of furosemide with serum thyroxine-binding sites: in vivo

and in vitro studies and comparison with other inhibitors., J Clin

Endocrinol Metab. 1985 May;60(5):1025-31. Stockigt JR, Lim CF, Barlow

JW, Wynne KN, Mohr VS, Topliss DJ, Hamblin PS, Sabto J.

The diuretic furosemide inhibits serum protein binding of T4 in

equilibrium dialysis, dextran-charcoal, and competitive ligand binding

separation systems and displaces [125I]T4 from isolated preparations of

T4-binding globulin (TBG), prealbumin, and albumin. Equilibrium dialysis

studies of undiluted normal serum showed that about 10 micrograms/ml

furosemide increased the free T4 and free T3 fractions. Displacement

occurred at lower drug concentrations in sera with subnormal albumin and

TBG levels. Binding of [14C]furosemide to TBG was inhibited by unlabeled

T4, suggesting that furosemide and T4 share a common binding site. A

single oral dose of 500 mg furosemide given to five patients maintained

on peritoneal dialysis increased the percentage of charcoal uptake of

[125I]T4 (using serum diluted 1:10) from 4.1 +/- 1.0 (+/- SE) to 10.8

+/- 4.3 (P less than 0.01) after 2 h, while decreasing total T3 from 75

+/- 5 to 56 +/- 13 ng/dl (P less than 0.01) and total T4 from 6.7 +/-

0.9 to 4.8 +/- 0.8 micrograms/dl (P less than 0.01) after 5 h. Various

ligands inhibited [125I]T4 binding to serum proteins in the following

relative molar relationship: T4, 1; furosemide, 1.5 X 10(3);

fenclofenac, 2 X 10(4); mefenamic acid. 2.5 X 10(4); diphenylhydantoin,

4 X 10[4); ethacrynic acid, 10(5); heparin 5 X 10(5);

2-hydroxybenzoylglycine, 10(6); and sodium salicylate, 1.5 X 10(6).

These studies demonstrate that furosemide competes for T4-binding sites

on TBG, prealbumin, and albumin, so that a single high dose can acutely

lower total T4 and T3 levels. The drug is much more potent on a molar

basis than other drug inhibitors of T4 binding, but at normal

therapeutic concentrations, furosemide is unlikely to decrease serum T4

or T3. However, high doses, diminished renal clearance, hypoalbuminemia,

and low TBG accentuate its T4- and T3-lowering effect. Hence, furosemide

should be considered a possible cause of low thyroid hormone levels in

patients with critical illness. The significance of this drug in reports

of impaired hormone and drug binding in renal failure requires further

assessment.

> 2. If this method is not good, what should I do instead?

>

Make sure your cardio knows you taking a thyroid med, or make sure your

thyroid doc knows about the furosemide. You may to adjust a dosage.

Chuck

------------------------------------

[Guest guest]

Roni,

You wrote:

>

> I forgot to tell you that I am on a very small dose, only 20 mgs. Does

> that make a difference?

Perhaps less likely but still a major possibility. You can tell how

finely tuned thyroid meds need to be by the increments of dosage.

Levothyroxine goes up by 12.5 mcg. I would imagine that 20 mg of

furosemide could easily create that big an effect on binding, especially

since only about 1% of T3 is free. A 1% reduction in binding means a

doubling of the free fraction.

When you have different doctors treating different conditions, they need

to be aware of what the other is prescribing.

Chuck

[Guest guest]

Thank you Chuck. I have an appointment next week and I will certainly bring this

up.

Roni

Chuck B <gumboyaya@...> wrote:

Roni,

You wrote:

>

> I forgot to tell you that I am on a very small dose, only 20 mgs. Does

> that make a difference?

Perhaps less likely but still a major possibility. You can tell how

finely tuned thyroid meds need to be by the increments of dosage.

Levothyroxine goes up by 12.5 mcg. I would imagine that 20 mg of

furosemide could easily create that big an effect on binding, especially

since only about 1% of T3 is free. A 1% reduction in binding means a

doubling of the free fraction.

When you have different doctors treating different conditions, they need

to be aware of what the other is prescribing.

Chuck

------------------------------------

[Guest guest]

asfy, thanks so much for these warnings. I'm going to pay attention and talk to my doctor. I'm really hoping use of these sprays is very short term -- I know one of them (not sure which yet) has no refills and is only a 14 day supply. thanks again.joanOn Oct 11, 2009, at 9:05 AM, asfy wrote:

Joan, I forgot to add that furosemide, among other things, can be

ototoxic (ie reduces hearing), but this effect is usually seen with

systemic administration ; a simultaneous steroid is also likely to

decrease such an effect. At any rate, watch out for any hearing loss

after prolonged use.