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Amiodarone-induced myxedema coma - a case and review of the literature.

Chakraborty S, Fedderson J, Gums JJ, Toole A - Arch Med Sci (2013)

View Article: PubMed Central - PubMed

Affiliation: University of Nebraska Medical Center, USA.

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A chest X ray revealed cardiomegaly without evidence of congestive heart failure and also showed increased soft tissue deposition in the cervical region (Figure 1A)... A computed tomography (CT) scan of the head without contrast did not show any hemorrhage, masses, fluid or midline shift that could explain this sudden deterioration of consciousness... Following initiation of the above treatment, the patient became progressively more alert and her jerking movements diminished... She was successfully extubated on the second day... He was noted to have an elevated serum TSH (66 μU/ml, normal range 1–8 μU/ml) and a low T4 (0.8 μg/dl, normal range 5–12 μg/dl) and T3 (29 ng/ml, normal range 70–150 ng/dl)... Female gender, older age, an underlying autoimmune thyroid disease, elevated baseline TSH levels, a starting dose of amiodarone > 200 mg/day, complex cyanotic heart disease and residence in an iodine sufficient region (e.g. United States) are considered to be risk factors for development of AIH... Amiodarone is hypothesized to cause hypothyroidism by a) releasing iodine (during its metabolism), which exerts a negative feedback effect reducing the uptake of iodine by and synthesis of T3 and T4 by the thyroid gland, b) inhibiting the enzyme 5’-deiodinase, thus inhibiting conversion of T4 to T3, c) inhibiting uptake of T4 by peripheral tissues, and d) inhibiting the effect of T3 on thyroid receptors (Figure 1B)... As the rate of conversion of T4 to T3 is decreased, supplemental T3 administration is suggested as a bolus of 10–20 μg followed by 10 μg intravenously every 4 h for the first 24 h, dropping to 10 μg every 6 h for days 2 and 3, after which oral administration can be resumed... Treatment of myxedema is associated with a risk of relative adrenal insufficiency secondary to enhanced peripheral metabolism of cortisol after T4 supplementation... Current evidence suggests that amiodarone can be continued in patients who receive concomitant levothyroxine supplementation... In those in whom stopping amiodarone therapy is appropriate, spontaneous remission of hypothyroidism usually occurs in 3–4 months... In conclusion, we report a case of myxedema coma presenting as worsening myoclonic jerks in a previously euthyroid patient on amiodarone therapy... It emphasizes the importance of maintaining a high index of suspicion for this complication in patients with a history of amiodarone therapy.

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Related in: MedlinePlus

A – Comparison of chest X-rays at presentation with pre-treatment and last known normal chest X ray. All images were taken in postero-anterior orientation unless specified. (Left) At presentation, it revealed cardiomegaly without evidence of pleural effusion. Some soft tissue swelling is noticeable in the cervical region. (Middle) Chest X ray obtained prior to starting amiodarone reveals presence of cardiomegaly without the prominent neck soft tissue. (Right) Chest X ray taken four years previously reveals normal heart size and no soft tissue swelling. B – Mechanisms by which amiodarone inhibits thyroid function. Amiodarone inhibits (A) the peripheral conversion of T4 to T3 by inhibiting the enzyme 5'-deiodinase that converts T4 to T3 both within peripheral tissues and within the pituitary gland, (B) the entry of T4 into the peripheral tissues, and (C) the effect of T3 on thyroid-responsive tissues. T3 is the major negative regulator of TSH synthesis in the pituitary. The decrease in level of intra-pituitary T3 leads to increased synthesis of TSH seen in amiodarone-induced hypothyroidism
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Figure 0001: A – Comparison of chest X-rays at presentation with pre-treatment and last known normal chest X ray. All images were taken in postero-anterior orientation unless specified. (Left) At presentation, it revealed cardiomegaly without evidence of pleural effusion. Some soft tissue swelling is noticeable in the cervical region. (Middle) Chest X ray obtained prior to starting amiodarone reveals presence of cardiomegaly without the prominent neck soft tissue. (Right) Chest X ray taken four years previously reveals normal heart size and no soft tissue swelling. B – Mechanisms by which amiodarone inhibits thyroid function. Amiodarone inhibits (A) the peripheral conversion of T4 to T3 by inhibiting the enzyme 5'-deiodinase that converts T4 to T3 both within peripheral tissues and within the pituitary gland, (B) the entry of T4 into the peripheral tissues, and (C) the effect of T3 on thyroid-responsive tissues. T3 is the major negative regulator of TSH synthesis in the pituitary. The decrease in level of intra-pituitary T3 leads to increased synthesis of TSH seen in amiodarone-induced hypothyroidism

Mentions: Initial investigations in the ER revealed leucocytosis (13.9 × 103/μl, normal 4.0–11.0 × 103/μl), anemia (11.1 g/dl, normal 11.0–15.0 g/dl) with macrocytosis (mean corpuscular volume 103.1 fl, normal 79.0–97.0 fl), mild hyponatremia (134 mEq/l, normal 136–145 mEq/l), hyperkalemia (6.9 mEq/l, normal 3.6–5.1 mEql/l) and uremia (urea nitrogen 59 mg/dl, normal 6–20 mg/dl, and creatinine 8.11 mg/dl, normal 0.44–1.03 mg/dl). Her baseline urea nitrogen and creatinine were 15 mg/dl and 3.35 mg/dl respectively. Urine analysis was positive for 10–50 bacteria, a moderate amount of leucocyte esterase, 0–4 white blood cells and no squamous cells/hpf. When the patient became stuporous on the floor, an arterial blood gas was obtained which revealed hypercarbic respiratory acidosis (pH 7.09, pO2 70 mm Hg, pCO2 87 mm Hg, bicarbonate 25 mmol/l) (Table I). Serum thyroid-stimulating hormone (TSH) was noted to be 77.25 μIU/ml (normal 0.4–5.0 μlU/ml), free T4 0.4 ng/ml (normal 0.6–1.5 ng/ml) and free T31.7 pg/ml (normal 2.5–3.9 pg/ml). A random serum cortisol was noted to be 4.5 μg/dl (normal 6.7–22.6 μg/dl). A chest X ray revealed cardiomegaly without evidence of congestive heart failure and also showed increased soft tissue deposition in the cervical region (Figure 1A). A computed tomography (CT) scan of the head without contrast did not show any hemorrhage, masses, fluid or midline shift that could explain this sudden deterioration of consciousness.


Amiodarone-induced myxedema coma - a case and review of the literature.

Chakraborty S, Fedderson J, Gums JJ, Toole A - Arch Med Sci (2013)

A – Comparison of chest X-rays at presentation with pre-treatment and last known normal chest X ray. All images were taken in postero-anterior orientation unless specified. (Left) At presentation, it revealed cardiomegaly without evidence of pleural effusion. Some soft tissue swelling is noticeable in the cervical region. (Middle) Chest X ray obtained prior to starting amiodarone reveals presence of cardiomegaly without the prominent neck soft tissue. (Right) Chest X ray taken four years previously reveals normal heart size and no soft tissue swelling. B – Mechanisms by which amiodarone inhibits thyroid function. Amiodarone inhibits (A) the peripheral conversion of T4 to T3 by inhibiting the enzyme 5'-deiodinase that converts T4 to T3 both within peripheral tissues and within the pituitary gland, (B) the entry of T4 into the peripheral tissues, and (C) the effect of T3 on thyroid-responsive tissues. T3 is the major negative regulator of TSH synthesis in the pituitary. The decrease in level of intra-pituitary T3 leads to increased synthesis of TSH seen in amiodarone-induced hypothyroidism
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4296056&req=5

Figure 0001: A – Comparison of chest X-rays at presentation with pre-treatment and last known normal chest X ray. All images were taken in postero-anterior orientation unless specified. (Left) At presentation, it revealed cardiomegaly without evidence of pleural effusion. Some soft tissue swelling is noticeable in the cervical region. (Middle) Chest X ray obtained prior to starting amiodarone reveals presence of cardiomegaly without the prominent neck soft tissue. (Right) Chest X ray taken four years previously reveals normal heart size and no soft tissue swelling. B – Mechanisms by which amiodarone inhibits thyroid function. Amiodarone inhibits (A) the peripheral conversion of T4 to T3 by inhibiting the enzyme 5'-deiodinase that converts T4 to T3 both within peripheral tissues and within the pituitary gland, (B) the entry of T4 into the peripheral tissues, and (C) the effect of T3 on thyroid-responsive tissues. T3 is the major negative regulator of TSH synthesis in the pituitary. The decrease in level of intra-pituitary T3 leads to increased synthesis of TSH seen in amiodarone-induced hypothyroidism
Mentions: Initial investigations in the ER revealed leucocytosis (13.9 × 103/μl, normal 4.0–11.0 × 103/μl), anemia (11.1 g/dl, normal 11.0–15.0 g/dl) with macrocytosis (mean corpuscular volume 103.1 fl, normal 79.0–97.0 fl), mild hyponatremia (134 mEq/l, normal 136–145 mEq/l), hyperkalemia (6.9 mEq/l, normal 3.6–5.1 mEql/l) and uremia (urea nitrogen 59 mg/dl, normal 6–20 mg/dl, and creatinine 8.11 mg/dl, normal 0.44–1.03 mg/dl). Her baseline urea nitrogen and creatinine were 15 mg/dl and 3.35 mg/dl respectively. Urine analysis was positive for 10–50 bacteria, a moderate amount of leucocyte esterase, 0–4 white blood cells and no squamous cells/hpf. When the patient became stuporous on the floor, an arterial blood gas was obtained which revealed hypercarbic respiratory acidosis (pH 7.09, pO2 70 mm Hg, pCO2 87 mm Hg, bicarbonate 25 mmol/l) (Table I). Serum thyroid-stimulating hormone (TSH) was noted to be 77.25 μIU/ml (normal 0.4–5.0 μlU/ml), free T4 0.4 ng/ml (normal 0.6–1.5 ng/ml) and free T31.7 pg/ml (normal 2.5–3.9 pg/ml). A random serum cortisol was noted to be 4.5 μg/dl (normal 6.7–22.6 μg/dl). A chest X ray revealed cardiomegaly without evidence of congestive heart failure and also showed increased soft tissue deposition in the cervical region (Figure 1A). A computed tomography (CT) scan of the head without contrast did not show any hemorrhage, masses, fluid or midline shift that could explain this sudden deterioration of consciousness.

View Article: PubMed Central - PubMed

Affiliation: University of Nebraska Medical Center, USA.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

A chest X ray revealed cardiomegaly without evidence of congestive heart failure and also showed increased soft tissue deposition in the cervical region (Figure 1A)... A computed tomography (CT) scan of the head without contrast did not show any hemorrhage, masses, fluid or midline shift that could explain this sudden deterioration of consciousness... Following initiation of the above treatment, the patient became progressively more alert and her jerking movements diminished... She was successfully extubated on the second day... He was noted to have an elevated serum TSH (66 μU/ml, normal range 1–8 μU/ml) and a low T4 (0.8 μg/dl, normal range 5–12 μg/dl) and T3 (29 ng/ml, normal range 70–150 ng/dl)... Female gender, older age, an underlying autoimmune thyroid disease, elevated baseline TSH levels, a starting dose of amiodarone > 200 mg/day, complex cyanotic heart disease and residence in an iodine sufficient region (e.g. United States) are considered to be risk factors for development of AIH... Amiodarone is hypothesized to cause hypothyroidism by a) releasing iodine (during its metabolism), which exerts a negative feedback effect reducing the uptake of iodine by and synthesis of T3 and T4 by the thyroid gland, b) inhibiting the enzyme 5’-deiodinase, thus inhibiting conversion of T4 to T3, c) inhibiting uptake of T4 by peripheral tissues, and d) inhibiting the effect of T3 on thyroid receptors (Figure 1B)... As the rate of conversion of T4 to T3 is decreased, supplemental T3 administration is suggested as a bolus of 10–20 μg followed by 10 μg intravenously every 4 h for the first 24 h, dropping to 10 μg every 6 h for days 2 and 3, after which oral administration can be resumed... Treatment of myxedema is associated with a risk of relative adrenal insufficiency secondary to enhanced peripheral metabolism of cortisol after T4 supplementation... Current evidence suggests that amiodarone can be continued in patients who receive concomitant levothyroxine supplementation... In those in whom stopping amiodarone therapy is appropriate, spontaneous remission of hypothyroidism usually occurs in 3–4 months... In conclusion, we report a case of myxedema coma presenting as worsening myoclonic jerks in a previously euthyroid patient on amiodarone therapy... It emphasizes the importance of maintaining a high index of suspicion for this complication in patients with a history of amiodarone therapy.

No MeSH data available.


Related in: MedlinePlus