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MyDeficiencies

Thyroid (desiccated)

Thyroid Hormone Replacement (natural desiccated extract)

Also sold as Armour Thyroid, NP Thyroid, Nature-Throid, WP Thyroid, Desiccated thyroid.

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Findings for this medication

Research about this medication, graded for how strongly each finding can be attributed to it. Nothing here describes your own levels.

Desiccated thyroid extract (NDT) has no classical depletion machinery of its own: it is not a CYP450 substrate or inducer, it does not chelate other nutrients, and it is not renally wasted. Its own labeled pharmacokinetics are variable GI absorption (48–79% bioavailable, improved by fasting), extensive hepatic and peripheral deiodination (about 80% of circulating T3 comes from monodeiodination of T4), and hepatic conjugation with biliary/renal elimination. The interactions that do exist run in the opposite direction from a depletion: calcium, iron salts, dietary fiber, soy, and bile-acid sequestrants (cholestyramine, colestipol) all reduce absorption of the drug itself and require dosing separation, they are not evidence the drug depletes those minerals.

thyroid hormone replacement (natural desiccated extract) · ATC H03AA05 · thyroid gland preparations · also sold as Armour Thyroid and NP Thyroid and Nature-Throid and WP Thyroid · reviewed 2026-09-23. This describes research about the medication. It does not say anything about your own levels or health.

How to read the evidence grades

These colours describe how strongly a finding can be attributed to the medication in the research. They are not a severity score and they say nothing about your own health.

Grades describe how strongly a finding can be attributed to Thyroid (desiccated) in the research — not how common it is, how serious it would be, and not anything about you personally.

Red — Severe
severe: two or more independent Tier A sources, this drug in the studied cohort, the nutrient directly measured, consistent direction and clinically meaningful magnitude, a named mechanism, no substantial contradicting Tier A evidence.
Orange — Moderate
moderate: at least one Tier A source with this drug in the cohort showing a real but bounded deficit (exposure window, subgroup, low frequency, or functional-only).
Yellow — Low
low/theoretical: mechanistic plausibility only (Tier B), or class extrapolation (Tier C) where at least one class member has real supporting data but this drug does not; also used for context flags and reverse-direction (excess/retention) findings.
Not graded — disclosed evidence gap
Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result.Source definition: evidence gap: genuinely searched, with neither Tier B/C support for a yellow grade nor a circulating claim to rebut as white. A disclosed absence of evidence, never reworded as reassurance.

What the research found

Vitamin B12

Yellow — Low

See study details

In one small before/after study of levothyroxine-treated hypothyroid women, serum cobalamin fell significantly after thyroid hormone replacement restored euthyroidism; no desiccated-thyroid-specific data exist.

Full detail and limits

What the grade means here: low/theoretical: mechanistic plausibility only (Tier B), or class extrapolation (Tier C) where at least one class member has real supporting data but this drug does not; also used for context flags and reverse-direction (excess/retention) findings. class extrapolation

Limits on what this shows

  • Key negative/null findings: Homocysteine improved (decreased significantly) with treatment despite falling cobalamin, arguing against a simple functional B12-deficiency picture in this cohort.
  • At-risk subgroups: None defined; single study, young/middle-aged women only.
  • Counter-evidence on record: No replication found in this review. Small sample (n=31). Levothyroxine only, not desiccated thyroid.

Regulatory status

Not addressed in the Armour Thyroid/NDT label; no FDA-labeled B12 warning.

Population evidence

Orzechowska-Pawilojc et al., Endocr J 2007: 31 hypothyroid women assessed before and after levothyroxine (T4-only) therapy, versus 30 healthy controls. Serum cobalamin was lower in the untreated hypothyroid state and "significantly decreased" further after treatment. Design: single-arm before/after cohort, not a controlled trial, and not NDT.

Mechanism

Not established. Possible increased metabolic/erythropoietic utilization of B12 as metabolic rate normalizes with treatment; not confirmed in this source.

Counter-evidence held on record

Rests on a single small levothyroxine study, not desiccated thyroid. Do not present as an established NDT effect, and do not recommend B12 supplementation on this basis alone.

Calcium and phosphorus

Yellow — Low

See study details

In endogenous hyperthyroidism, serum calcium rises and serum phosphorus falls; this is the mechanistic pattern expected if NDT over-replacement produces a hyperthyroid state, a mobilization/excess risk, not a deficiency.

Full detail and limits

What the grade means here: low/theoretical: mechanistic plausibility only (Tier B), or class extrapolation (Tier C) where at least one class member has real supporting data but this drug does not; also used for context flags and reverse-direction (excess/retention) findings. excess/retention direction · disease-state extrapolation

Limits on what this shows

  • Key negative/null findings: None specific to over-replacement found in this review.
  • At-risk subgroups: Patients on supraphysiological or poorly titrated NDT dosing (harder to fine-tune than levothyroxine because of its fixed T4:T3 ratio), pre-existing osteoporosis, postmenopausal women.
  • Counter-evidence on record: Confounding by indication applies directly (Hard Rule 6): this cohort had endogenous hyperthyroid disease, not iatrogenic NDT over-replacement, so the drug's specific contribution beyond the disease state is not established.

Regulatory status

The label does not quantify mineral effects; it does caution that thyroid hormones should be used with great caution and low starting doses in patients with cardiac disease, consistent with over-treatment risk generally.

Population evidence

Athokpham, Mohanty & Pinnelli, Asian J Pharm Clin Res 2020: case-control study, 60 newly diagnosed (endogenous) hyperthyroid patients versus 60 euthyroid controls. Serum calcium significantly higher (p<0.001, positively correlated with T3/T4/FT3/FT4, negatively with TSH); serum phosphorus significantly lower (p<0.001, correlated in the opposite direction). This is a disease-state cohort, not NDT-treated or iatrogenically over-replaced patients — class/disease extrapolation for this drug.

Mechanism

Thyroid hormone excess increases bone resorption/turnover and alters renal phosphate handling, established endocrine physiology; not independently re-derived in this review beyond the cited source.

Counter-evidence held on record

This is an EXCESS/retention-direction finding, not a deficiency. Never recommend calcium or vitamin D supplementation in response to this entry. The appropriate response to suspected over-replacement is thyroid dose reduction under a prescriber, guided by TSH/FT4 monitoring, not mineral supplementation.

No entries required ungraded status

Not graded — disclosed evidence gap

See study details

Every nutrient or category carried forward from the mechanism and category screens resolved to at least a YELLOW grade (Tier B/C evidence found) or a WHITE fails-verification entry (a circulating claim found and rebutted), so none met the dual-condition UNGRADED test in this review.

Full detail and limits

What the grade means here: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result. none

Limits on what this shows

  • Why no grade: Not applicable — this section is empty by outcome, not by omission. Per Step 7, UNGRADED requires both no Tier B/C support AND no circulating claim to rebut; every screened item here cleared at least one of those bars.

Tooling note

Some candidate areas (iron status change with treatment specifically, vitamin D and thyroid hormone treatment specifically, selenium/deiodinase cofactor literature) were identified via search listings but could not be opened before this session's WebSearch budget was exhausted and WebFetch access to PubMed/PMC/Semantic Scholar/Crossref became rate-limited; they were left out of the graded entries entirely rather than graded from an unopened source, and should be revisited in a follow-up review with full tool access rather than assumed ungraded or safe.

The five body-system areas

Each finding is counted once, in a single area. Where a study is mentioned in a second area it is context only.

Mitochondrial Burden

Each finding below is counted once, in this area only.

Mitochondrial burden

Yellow — Low

See study details

Thyroid hormone (T4/T3, regardless of source) directly stimulates mitochondrial biogenesis and respiratory-chain gene transcription; this is the intended therapeutic mechanism of thyroid hormone replacement, not a depletion, though it plausibly raises mitochondrial workload at supraphysiological exposure.

Full detail and limits

What the grade means here: low/theoretical: mechanistic plausibility only (Tier B), or class extrapolation (Tier C) where at least one class member has real supporting data but this drug does not; also used for context flags and reverse-direction (excess/retention) findings. mechanism-only · intended pharmacology

Limits on what this shows

  • Key negative/null findings: None found; this is a mechanistic review, not a human outcome study.
  • At-risk subgroups: Patients on supraphysiological/over-replacement dosing, where the mechanism is most active.
  • Counter-evidence on record: This is the drug's own intended pharmacologic mechanism (restoring metabolic rate in hypothyroidism), per Hard Rule 2 it is framed here as a workload/plausibility flag, not a proven adverse depletion effect.

Regulatory status

The label states thyroid hormones "enhance oxygen consumption by most tissues" and affect carbohydrate, lipid, and protein metabolism broadly, consistent with this mechanism at the whole-body level.

Population evidence

None found in NDT- or levothyroxine-treated human cohorts directly measuring mitochondrial burden markers. Mechanism-only (Tier B).

Mechanism

Cioffi, Giacco, Goglia & Silvestri, Cells 2022 (animal/in vitro mechanistic review): T3 binding to nuclear and mitochondrial receptors (including the p43 mitochondrial isoform) activates transcription of nuclear- and mitochondrial-genome-encoded respiratory-chain genes and increases electron flux through the respiratory complexes.

Counter-evidence held on record

Do not present as an adverse effect of NDT. This is the mechanism by which thyroid hormone treats hypothyroidism; it becomes a workload concern mainly if dosing runs above physiologic replacement.

Oxidative Stress

Each finding below is counted once, in this area only.

Oxidative stress

Yellow — Low

See study details

Untreated hypothyroidism is associated with elevated lipid peroxidation (MDA) that does not correlate with thyroid hormone levels themselves; a separate, mechanism-only pathway (reduced mitochondrial coupling efficiency at high thyroid hormone exposure) could theoretically raise ROS generation with over-replacement, but this was not measured in treated patients.

Full detail and limits

What the grade means here: low/theoretical: mechanistic plausibility only (Tier B), or class extrapolation (Tier C) where at least one class member has real supporting data but this drug does not; also used for context flags and reverse-direction (excess/retention) findings. disease-state human data · mechanism-only for the drug

Limits on what this shows

  • Key negative/null findings: In the human cohort, MDA was "not associated with TSH...FT4 and FT3" but did correlate with elevated cholesterol and LDL, arguing the oxidative signal tracks lipid status more than thyroid hormone level directly.
  • At-risk subgroups: None defined for NDT specifically.
  • Counter-evidence on record: The only human data found implicate the untreated disease state, not thyroid hormone treatment, as associated with the oxidative marker measured.

Regulatory status

Not addressed in the label.

Population evidence

Cross-sectional study (PMC4922350): 467 men with subclinical hypothyroidism (untreated, thyroxine-naive) versus 190 euthyroid controls. Plasma MDA significantly higher in subclinical hypothyroidism (8.11±1.39 vs 7.34±1.31 nmol/mL, p<0.05); total antioxidant capacity unchanged between groups; protein-oxidation markers (AOPP, dityrosine) not significantly different. This cohort explicitly excluded thyroxine-treated patients, disease-state evidence only, not drug evidence.

Mechanism

Cioffi et al., Cells 2022 (animal/in vitro): reduced mitochondrial respiratory supercomplex assembly and UCP2 activation by ROS/lipid-peroxidation products are proposed to modulate ROS generation under altered thyroid hormone exposure.

Counter-evidence held on record

Available human evidence points to untreated hypothyroidism itself, not NDT or thyroid hormone treatment, as associated with oxidative markers. Do not present thyroid hormone treatment as the cause of oxidative stress on this evidence.

Copper and Iron Balance

Copper and iron are assessed separately. Nothing here is counted twice.

Copper

Yellow — Low

See study details

In endogenous hyperthyroidism, serum copper is significantly elevated relative to euthyroid controls; an excess-direction, disease-state signal, not a depletion.

Full detail and limits

What the grade means here: low/theoretical: mechanistic plausibility only (Tier B), or class extrapolation (Tier C) where at least one class member has real supporting data but this drug does not; also used for context flags and reverse-direction (excess/retention) findings. excess/retention direction · disease-state extrapolation

Limits on what this shows

  • Key negative/null findings: Copper level was not correlated with the actual degree of thyroid hormone elevation in this cohort, weakening a simple dose-response case.
  • At-risk subgroups: None defined for NDT specifically.
  • Counter-evidence on record: Confounding by indication applies (Hard Rule 6): disease-state cohort, not iatrogenic over-replacement.

Regulatory status

Not addressed in the label.

Population evidence

Athokpham, Mohanty & Pinnelli, Asian J Pharm Clin Res 2020 (same cohort as the calcium/phosphorus entry above): serum copper significantly higher in hyperthyroid cases versus controls (p<0.001), though "no suggestive significant correlation was found between serum copper with serum T3, T4, TSH, FT3, and FT4." Disease-state cohort, not NDT-treated — class/disease extrapolation.

Mechanism

Not established in this source; ceruloplasmin (a copper-carrying acute-phase-like protein) is known in general endocrine physiology to shift with thyroid status, but that specific pathway was not independently verified in this review.

Counter-evidence held on record

Excess-direction finding. Do not restrict dietary copper or use this as grounds for a copper-related supplement claim in either direction. Monitor via TSH/FT4, not serum copper.

Gut Microbiome Risk

Each finding below is counted once, in this area only.

Gut microbiome risk

Yellow — Low

See study details

Levothyroxine dose stability correlates with gut microbiome composition in subclinical hypothyroidism, but whether the microbiome affects the drug's required dose or the drug alters the microbiome is not established; no desiccated-thyroid-specific data exist.

Full detail, limits and 1 references

What the grade means here: low/theoretical: mechanistic plausibility only (Tier B), or class extrapolation (Tier C) where at least one class member has real supporting data but this drug does not; also used for context flags and reverse-direction (excess/retention) findings. class extrapolation · direction unresolved

Limits on what this shows

  • Key negative/null findings: The study could not and did not establish that starting treatment caused the compositional differences observed; it is a cross-sectional association, not a before/after design.
  • At-risk subgroups: None defined.
  • Counter-evidence on record: Direction of causality is ambiguous in the source itself; only levothyroxine studied, not desiccated thyroid.

Regulatory status

Not addressed in the label.

Population evidence

Cross-sectional fecal-sample study, Frontiers in Cellular and Infection Microbiology 2020: 117 subjects (49 on L-thyroxine, 68 controls). Microbiome composition, including taxa such as Alistipes, Ruminococcus, and Anaerotruncus, varied between patients whose LT4 dose remained stable versus those requiring dose increases over nine months. Levothyroxine only, not NDT.

Mechanism

Proposed bacterial glucuronidase/sulfatase activity affecting thyroxine's enterohepatic handling, a nutrient/microbiome-affects-drug mechanism, not clearly a drug-affects-microbiome mechanism.

Counter-evidence held on record

Do not present as "thyroid medication damages gut bacteria." The evidence found shows an association with dose requirement, not proof that the drug alters the microbiome, and no NDT-specific study exists.

Oxygen and ATP Output

Oxygen delivery and ATP production are assessed separately. Nothing here is counted twice.

ATP production

Yellow — Low

See study details

Thyroid hormone increases mitochondrial oxidative phosphorylation rate but, per the mitochondrial "uncoupling" mechanism, can reduce ATP yield per unit of oxygen consumed at high exposure; an efficiency effect intrinsic to thyroid hormone pharmacology, not a nutrient-cofactor depletion.

Full detail and limits

What the grade means here: low/theoretical: mechanistic plausibility only (Tier B), or class extrapolation (Tier C) where at least one class member has real supporting data but this drug does not; also used for context flags and reverse-direction (excess/retention) findings. mechanism-only · intended pharmacology at excess dose

Limits on what this shows

  • Key negative/null findings: None found.
  • At-risk subgroups: Patients on supraphysiological or over-replacement dosing, consistent with the drug's known thermogenic mechanism and the label's cardiac caution.
  • Counter-evidence on record: None found.

Regulatory status

The label's cardiac caution (start at low dose, 15–30 mg, in patients with suspected coronary disease) is consistent with the increased metabolic/oxygen demand this mechanism describes.

Population evidence

None found in human NDT- or levothyroxine-treated cohorts directly measuring ATP yield. Mechanism-only (Tier B).

Mechanism

Cioffi et al., Cells 2022 (animal/in vitro): thyroid hormone reduces mitochondrial coupling via proton-leak mechanisms, lowering the P/O ratio (phosphate incorporated per oxygen consumed), part of its calorigenic/thermogenic action, the "uncoupling hypothesis."

Counter-evidence held on record

This describes a pharmacologic/thermogenic mechanism of thyroid hormone itself, more pronounced with over-replacement, not evidence that NDT depletes cellular energy or requires ATP-supporting supplementation.

Claims checked and not supported

These circulate online for this medication. They are listed here only so they can be answered, never as findings, and they are not graded.

A claim with no supporting evidence is not necessarily disproven. Where evidence actually argues against a claim, that is stated below.

  • Iron

    Where it comes from: Common consumer framing that thyroid medication "depletes" or causes iron deficiency.

    Why it fails: The documented drug-nutrient relationship runs the opposite direction: oral iron salts and iron-containing multivitamins reduce absorption of thyroid hormone itself (a timing interaction, ≥4 hours separation advised per the label and Drugs.com interaction data), not the reverse. Iron-deficiency anemia seen in hypothyroid patients reflects the underlying disease (reduced erythropoietin drive, achlorhydria-related malabsorption), a confound by indication (Hard Rule 6), not a drug-caused loss. No Tier A/B evidence found that NDT or levothyroxine directly depletes iron stores.

  • Folate

    Where it comes from: General "thyroid medication depletes B-vitamins" framing that lumps folate in with B12.

    Why it fails: The one before/after human study found (Orzechowska-Pawilojc et al. 2007) measured folate directly in levothyroxine-treated hypothyroid women and found it "remained unchanged" after treatment, a direct null finding against the depletion claim, for the T4 component specifically.

  • Magnesium

    Where it comes from: Claims that increased metabolic rate from thyroid hormone increases magnesium demand.

    Why it fails: The one case-control human study found (Athokpham et al. 2020) measured serum magnesium directly in endogenous hyperthyroidism, a stronger metabolic-demand state than typical replacement dosing, and found no significant difference from euthyroid controls (p=0.556) and no correlation with thyroid hormone levels.

  • Iodine

    Where it comes from: Consumer content suggesting thyroid medication depletes iodine or that iodine supplementation should accompany it.

    Why it fails: Desiccated thyroid extract is itself iodine-containing (historically standardized by iodine assay, roughly 0.17–0.23% per USP methods, per composition references); exogenous thyroid hormone suppresses TSH and thereby reduces thyroidal iodine-uptake drive rather than depleting body iodine stores. The claimed direction is reversed.

  • Oxygen delivery/utilization

    Where it comes from: Consumer framing that thyroid medication (or hypothyroidism) "starves tissues of oxygen" or impairs oxygen delivery.

    Why it fails: Per the drug's own labeled mechanism of action, thyroid hormones "enhance oxygen consumption by most tissues of the body," the opposite direction of a deficiency. The genuine clinical concern in this domain runs the other way: increased myocardial oxygen demand in patients with occult coronary disease, which is why the label recommends cautious low-dose initiation in such patients. This is a safety/mechanism issue, not a nutrient-style oxygen-delivery deficiency (Hard Rule 2).

All references used above
  1. DailyMed — ARMOUR THYROID (thyroid, porcine) tablet, FDA prescribing information — Regulatory label. Used for mechanism of action, absorption, metabolism, elimination, and drug-interaction facts.
  2. Drugs.com — food and mineral interactions for thyroid desiccated / Armour Thyroid — Tier D reference database; used only for interaction-direction and separation-interval facts consistent with the label.
  3. WHO Collaborating Centre for Drug Statistics Methodology — ATC/DDD Index, group H03AA (Thyroid hormones) — Confirms ATC H03AA05 "thyroid gland preparations" as the code for desiccated thyroid, distinct from H03AA01 (levothyroxine sodium) and H03AA02 (liothyronine sodium).
  4. Wikipedia — "Desiccated thyroid extract" — Tier D background source; used only for composition (approximate 4:1 T4:T3 ratio per grain, historical iodine-content assay standard) and regulatory/brand history, not for clinical claims.
  5. 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):1982-1990. — Randomized double-blind crossover trial, n=70 hypothyroid patients, DTE vs levothyroxine, 16 weeks each arm. DTE in cohort directly. Measured weight, symptoms, neurocognitive tests, quality of life and preference; did not measure nutrient or physiological-category markers. PMID 23539727, DOI 10.1210/jc.2012-4107.
  6. Orzechowska-Pawilojc A, Sworczak K, Lewczuk A, Babinska A. Homocysteine, folate and cobalamin levels in hypothyroid women before and after treatment. Endocr J. 2007;54(3):471-476. — Before/after cohort, n=31 hypothyroid women (levothyroxine) vs 30 healthy controls.Desiccated thyroid was not studied (levothyroxine only) — class extrapolation for NDT.
  7. Athokpam D, Mohanty S, Pinnelli VB. Alterations of serum calcium, phosphorus, magnesium, and copper in hyperthyroidism patients: a case-control study. Asian J Pharm Clin Res. 2020;13(12). DOI 10.22159/ajpcr.2020.v13i12.39611. — Case-control study, n=60 newly diagnosed hyperthyroid patients vs 60 euthyroid controls.No thyroid hormone drug (NDT or levothyroxine) in the cohort; endogenous disease state only — disease-state extrapolation for this drug.
  8. Cioffi F, Giacco A, Goglia F, Silvestri E. Bioenergetic Aspects of Mitochondrial Actions of Thyroid Hormones. Cells. 2022;11(6):997. DOI 10.3390/cells11060997. — Mechanistic review of animal and in vitro studies on thyroid hormone, mitochondrial biogenesis, oxidative phosphorylation, the uncoupling/P-O-ratio hypothesis, and ROS/UCP2 pathways. No NDT-specific or human clinical data.
  9. "Association Between Thyroid Hormones, Lipids and Oxidative Stress Markers in Subclinical Hypothyroidism" — Cross-sectional study, n=467 men with subclinical hypothyroidism (thyroxine-naive) vs 190 euthyroid controls. Measured MDA, total antioxidant capacity, AOPP, dityrosine.Thyroxine-treated patients were explicitly excluded from this cohort — disease-state evidence only, not drug evidence.
  10. "Relation of Gut Microbes and L-Thyroxine Through Altered Thyroxine Metabolism in Subclinical Hypothyroidism Subjects," Frontiers in Cellular and Infection Microbiology, 2020. — Cross-sectional fecal-microbiome study, n=117 (49 on L-thyroxine, 68 controls).Levothyroxine only, not desiccated thyroid — class extrapolation for NDT.
  11. Narrative review on liquid/softgel levothyroxine formulations overcoming tablet-absorption interference from calcium carbonate and ferrous sulfate, Frontiers in Endocrinology, 2022 (fendo.2022.1080108). — Tier C narrative review citing further primary studies (Benvenga 2014, Brancato 2014, Vita 2017) that were not independently opened in this review; used here only for the general, well-corroborated direction of the calcium/iron-reduces-levothyroxine-absorption interaction, consistent with the DailyMed label.
  12. PubMed search listing: "desiccated thyroid extract nutrient" — 11 results spanning 1960-2026, none specific to desiccated thyroid extract's effect on a classical nutrient or any of the seven physiological categories. Documents the genuine absence of NDT-specific nutrient-interaction literature that underlies this dossier's class-extrapolation framing throughout.