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Armour Thyroid and Liver Function: What the Evidence Actually Shows

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At a glance

  • Drug / Armour Thyroid, a porcine desiccated thyroid extract
  • Hormone content / 38 mcg T4 and 9 mcg T3 per 60 mg (1 grain) [1]
  • Trial outcomes reported / Symptoms, cognition, weight, treatment preference, heart rate [3][4]
  • Hypothyroidism and enzymes / Mean ALT 29 to 41 U/L and GGT 36 to 62 U/L as TSH rose in 10,292 outpatients [2]
  • Label adverse reactions / Rare apart from those of hyperthyroidism from overdosage [1]
  • Overdose picture / Hypermetabolic state; dose reduced or temporarily stopped [1]
  • FDA status / Not approved by FDA as a new drug [1]

Is there direct evidence that Armour Thyroid affects the liver?

The two head-to-head trials of desiccated thyroid extract report no liver results [3][4]. Hoang and colleagues gave 70 adults with primary hypothyroidism 16 weeks of desiccated thyroid extract and 16 weeks of levothyroxine in either order. Symptoms and neurocognitive tests did not differ, weight was 3 lb lower on the extract (172.9 vs 175.7 lb, P<.001), and 34 patients (48.6%) preferred the extract [4]. Shakir and colleagues randomized 75 patients to levothyroxine, levothyroxine plus liothyronine, or desiccated thyroid extract for 22 weeks. TSH stayed in range in all arms, and there were no differences in primary or secondary outcomes apart from a minor heart-rate increase on the extract; secondary endpoints included biochemical and metabolic parameters [3].

What hypothyroidism itself does to liver enzymes

In a retrospective analysis of 10,292 outpatient adults, mean ALT rose from 29 to 41 U/L and mean GGT from 36 to 62 U/L across rising TSH categories, and the association held after adjusting for sex, age, lipids and fasting glucose [2]. Higher free T4 went with lower enzyme values in the same cohort [2]. This is an association in a retrospective analysis, not proof of cause. In a cross-sectional study of 4,648 health-checkup subjects, abnormal ALT became more common as hypothyroidism worsened, at 20.1% in subclinical and 25.9% in overt hypothyroidism [5].

What the Armour Thyroid label says

The label states that adverse reactions other than those indicative of hyperthyroidism from therapeutic overdosage are rare [1]. According to the label, excessive doses produce a hypermetabolic state; it says the dose should be reduced or therapy temporarily discontinued, with propranolol and supportive care for severe overdose [1]. It lists chest pain, rapid pulse, palpitations, sweating, heat intolerance and nervousness among the effects to report [1].

Frequently asked questions

Can Armour Thyroid cause liver damage?
That is not established. The Armour Thyroid label says adverse reactions other than those of hyperthyroidism from overdosage are rare, and it describes excessive dosing as producing a hypermetabolic state [1].
Does hypothyroidism raise liver enzymes?
In 10,292 outpatient adults, mean ALT rose from 29 to 41 U/L and mean GGT from 36 to 62 U/L across rising TSH categories [2]. Abnormal ALT was also more frequent with worsening hypothyroidism in a study of 4,648 health-checkup subjects, at 20.1% subclinical versus 25.9% overt [5].
Why does the T3 content of Armour Thyroid get attention?
One grain (60 mg) contains 38 mcg T4 and 9 mcg T3 [1]. The ratio in desiccated thyroid is about 4.2 parts T4 to 1 part T3, against roughly 14:1 for human thyroid secretion, and the American Thyroid Association guideline notes that this can produce supraphysiologic serum T3 levels shortly after a dose [6]. The guideline recommends levothyroxine in preference to thyroid extracts, citing supraphysiologic T3 levels and little long-term safety data [6].
Is Armour Thyroid linked to fatty liver disease?
The reported association is with hypothyroidism rather than with the tablets. Among 9,419 Rotterdam Study participants followed for a median of about 10 years, hypothyroidism was associated with a 1.24-fold higher risk of fatty liver, and higher TSH with higher odds of clinically relevant fibrosis in fatty liver (odds ratio 1.49) [7]. A systematic review of 11 studies found the results inconsistent [8].

References

  1. U.S. National Library of Medicine, DailyMed. Armour Thyroid (thyroid tablets, USP), AbbVie/Allergan prescribing information. Armour Thyroid (thyroid tablets, USP), AbbVie/Allergan label
  2. Targher G, Montagnana M, Salvagno G, Moghetti P, Zoppini G, Muggeo M, et al. Association between serum TSH, free T4 and serum liver enzyme activities in a large cohort of unselected outpatients. Clin Endocrinol (Oxf). 2008;68(3):481-4. Association between serum TSH, free T4 and serum liver enzyme activities in a large cohort of unselected outpatients
  3. Shakir MKM, Brooks DI, McAninch EA, Fonseca TL, Mai VQ, Bianco AC, et al. Comparative Effectiveness of Levothyroxine, Desiccated Thyroid Extract, and Levothyroxine+Liothyronine in Hypothyroidism. J Clin Endocrinol Metab. 2021;106(11):e4400-e4413. Comparative Effectiveness of Levothyroxine, Desiccated Thyroid Extract, and Levothyroxine+Liothyronine in Hypothyroidism
  4. Hoang TD, Olsen CH, Mai VQ, Clyde PW, Shakir MK. Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: a randomized, double-blind, crossover study. J Clin Endocrinol Metab. 2013;98(5):1982-90. Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: a randomized, double-blind, crossover study
  5. Chung GE, Kim D, Kim W, Yim JY, Park MJ, Kim YJ, et al. Non-alcoholic fatty liver disease across the spectrum of hypothyroidism. J Hepatol. 2012;57(1):150-6. Non-alcoholic fatty liver disease across the spectrum of hypothyroidism
  6. Jonklaas J, Bianco AC, Bauer AJ, Burman KD, Cappola AR, Celi FS, et al. Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement. Thyroid. 2014;24(12):1670-751. Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement
  7. Bano A, Chaker L, Plompen EP, Hofman A, Dehghan A, Franco OH, et al. Thyroid Function and the Risk of Nonalcoholic Fatty Liver Disease: The Rotterdam Study. J Clin Endocrinol Metab. 2016;101(8):3204-11. Thyroid Function and the Risk of Nonalcoholic Fatty Liver Disease: The Rotterdam Study
  8. Eshraghian A, Hamidian Jahromi A. Non-alcoholic fatty liver disease and thyroid dysfunction: a systematic review. World J Gastroenterol. 2014;20(25):8102-9. Non-alcoholic fatty liver disease and thyroid dysfunction: a systematic review
Evidence overview for armour thyroid: Armour Thyroid and Liver Function: What the Evidence Actually Shows