Our pharmacist member, Tony Kinkade provides a precise explanation of the issues created by apparent differences in milligram (mg) dosages of dessicated thyroid.
Tony writes:
Armour Thyroid…is it really 60 mg? Actually, it’s 64.8 mg. The apothecary weight system was used in pharmacy back in the old days and has been replaced by the metric system. 1 grain is a weight measurement that is equivalent to 64.8 mg. Armour Thyroid is really 1 grain. However, depending on the person or manufacturer, 1 grain can be expressed as 60, 64.8 or 65 milligrams. If you are on 1 grain Armour Thyroid, you are really on 64.8 mg, but the stock bottle says 60 mg (they are allowed to do that). So one manufacturer will express 1 grain as 60 mg and another as 65 mg. Why not use 64.8 mg? They can. They just choose to round up or down for simplicity. And…manufacturers can vary a bit on either side of the true weight and still be compliant to FDA rules.
Don’t fret over it.
Remember, there are fewer strengths of dessicated thyoid available than levothyroxine has. So dosing precision isn’t the same. 1/2 gr to 1 gr to 1 & 1/2 gr (30 mg to 60 mg to 90 mg) for dessicated thyroid are much larger jumgs than 75 mcg to 88 mg to 100 mcg to 112 mcg to 125 mcg to 137 mcg to 150 mcg for levothyroxine.
Armour Thyroid…is it really 60 mg? Actually, it’s 64.8 mg. The apothecary weight system was used in pharmacy back in the old days and has been replaced by the metric system. 1 grain is a weight measurement that is equivalent to 64.8 mg. Armour Thyroid is really 1 grain. However, depending on the person or manufacturer, 1 grain can be expressed as 60, 64.8 or 65 milligrams. If you are on 1 grain Armour Thyroid, you are really on 64.8 mg, but the stock bottle says 60 mg (they are allowed to do that). So one manufacturer will express 1 grain as 60 mg and another as 65 mg. Why not use 64.8 mg? They can. They just choose to round up or down for simplicity. And…manufacturers can vary a bit on either side of the true weight and still be compliant to FDA rules.
Don’t fret over it.
Remember, there are fewer strengths of dessicated thyoid available than levothyroxine has. So dosing precision isn’t the same. 1/2 gr to 1 gr to 1 & 1/2 gr (30 mg to 60 mg to 90 mg) for dessicated thyroid are much larger jumgs than 75 mcg to 88 mg to 100 mcg to 112 mcg to 125 mcg to 137 mcg to 150 mcg for levothyroxine.
kingkade@san.rr.com
Tony Kingkade
1
