The cause of primary hypothyroidism in an adult will usually be determined from a history of thyroidectomy or radiotherapy or finding high titres of antithyroid antibodies (thyroid peroxidase, antimicrosomal or antithyroglobulin antibodies).A month's supply can be kept at room temperature. 4 Starting thyroxine. The rate of introduction of thyroxine should be determined by the duration of the hypothyroidism and the presence (or risk) of coronary disease or heart failure.
Lifelong thyroxine therapy relieves symptoms and restores 'normal' thyroid function. Commencing thyroxine can aggravate cardiac disease but is relatively free of adverse effects. The concentration of thyroid stimulating hormone is used to monitor therapy.At the start of treatment a patient does not need measurement of their TSH until they have been on their predicted dose of thyroxine for 4-6 weeks (unless symptoms of thyrotoxicosis dictate otherwise).
4 Although I have occasionally performed this test, I do not find it to be generally helpful unless it demonstrates completely 'normal results, thereby supporting patient noncompliance. Unfortunately, there.When the thyroxine dose is in the range of 100-200 microgram/day, variable daily dosing may be necessary to achieve euthyroidism. Considering the total weekly dose is helpful when changing the dose.
A list of medications that may interfere is included in. Table 1, but this list is certainly incomplete as new offending medications are reported frequently. (5) Investigate for malabsorption. Unfortunately, levothyroxine is not fully absorbed after oral ingestion.A fairly large and still growing number of medications, supplements and even food items can alter the fraction of an ingested dose that is absorbed. 3,4 The ingestion of one or more of these items at or near the time of dosing with thyroxine can substantially change the dose requirement in an individual patient, especially.
If the patient has frequent, voluminous stools, a malabsorption disorder may be evident and measurements of stool fat can confirm this diagnosis. However, thyroxine malabsorption has been reported as the initial finding in patients with otherwise asymptomatic malabsorptive syndromes, especially coeliac disease.For example, a recent patient I was referred was a 40-year-old woman from a neighbouring community who was diagnosed with hypothyroidism 1 year prior to her visit. In brief, at that time she expressed symptoms compatible with hypothyroidism, such as severe constipation, fatigue and a modest amount of weight gain, and her thyroid gland was.
Treatment requires taking thyroid hormone pills. TSH: thyroid stimulating hormone produced by the pituitary gland that regulates thyroid function; also the best screening test to determine if the thyroid is functioning normally.At 2 years, 75 of patients on doses of 125 mcg or less continued to have TSH levels in the normal range, but only 45 of patients on more than 125 mcg/day had continued normal TSH values.
If the patient discovers they have missed one (or more) doses they can take the missed doses in conjunction with their usual dose over the next few days. The absorption of thyroxine may be reduced by cholestyramine, colestipol, aluminium hydroxide, ferrous sulfate and possibly fibre.After taking 300 g of levothyroxine for 6 weeks, she was referred for further evaluation when her TSH remained elevated (77 mIU/l) and free thyroxine remained low at 77 pmol/l. My approach to this patient and those with persistently elevated TSH levels despite doses of thyroid hormone that should be adequate is outlined below.
(2) Ask about compliance. The most common reason for unusually high thyroid hormone dose requirements in my practice is poor compliance with the daily dosing of levothyroxine. One day's tablet accounts for 14 of the total weekly dose and because of the long half-life of levothyroxine, missing a day will have an influence on thyroid.After diagnosis, treatment is usually begun with daily levothyroxine (L-T4) pills with a goal of restoring the TSH level to the normal range and improving the symptoms of hypothyroidism. Thereafter, current guidelines recommend measuring the TSH level once or twice a year to ensure the L-T4 dose is appropriate as some patients may require a.
This is increased at intervals of 3-4 weeks until the predicted dose is reached. Patients should feel some symptomatic improvement within two weeks of starting thyroxine. It may take 3-4 months for the full benefit of the drug to become apparent and for the TSH to normalise.Measurement of free T4 and/or free T3 by equilibrium dialysis may at times be helpful as these more direct methods of assay are less susceptible to the effects of thyroxine binding proteins.
A morning cortisol less than 100 nmol/L always indicates the need for ongoing steroid replacement. Results greater than 500 nmol/L indicate adequate reserve and values in between may require provocation tests.Malabsorption syndromes increase the requirement for levothyroxine by further reducing the fraction of the ingested dose that is absorbed. Patients with short bowel from prior small bowel bypass or resection commonly require higher than expected T4 doses.
Markedly elevated TSH levels without low or at least low-normal thyroid hormones suggests other diagnoses or reasons for the discrepant dose requirements such as heterophilic antibody interference with TSH measurements, TSH secreting pituitary tumours, or thyroid hormone resistance syndromes.However, one of the common clinical problems that I am asked to review is that of the patient who requires higher doses of levothyroxine for normalization of their TSH or whose TSH level remains persistently elevated despite these high doses.
Repeat testing every six weeks is appropriate until the dose is stabilised, however if the patient is approaching euthyroidism and is feeling well this interval can be increased. After the dose is stabilised an annual TSH measurement is usually adequate monitoring unless a problem arises.Antibiotic treatment of the. H. pylori infection was also demonstrated to improve absorption and reduce thyroxine requirement in those patients. 7 (6) Consider increased turnover or excretion. A number of drugs or clinical conditions may increase the turnover or excretion of thyroid hormone and thereby increase considerably the requirement in individuals that are thyroid hormone.
The study found that the only risk factor for having an abnormal TSH level was the dose of L-T4 that a patient was taking. Those taking more than 125 mcg of L-T4 per day were much less likely to maintain normal TSH levels over time than those taking less than 125 mcg per day.WHAT ARE THE IMPLICATIONS OF THIS STUDY? This study suggests that hypothyroid patients on L-T4 doses 125 mcg daily have more stable TSH levels than those on higher doses. This may be due to some residual thyroid function that can help maintain normal TSH levels ion patients on lower doses.
Confirming records of prescriptions and refill records with the pharmacy may also be helpful in documenting compliance, or lack thereof. (4) Review the thyroxine ingestion history. The most efficient and reproducible way of taking levothyroxine is to ingest the tablets on an empty stomach and avoid ingesting other medications or food for 3060 min afterwards.It is diagnosed by an elevated TSH level and low T4 levels. Primary hypothyroidism is very common, particularly in women, and is reported to affect at least 5 of the US population.
Thyroxine can be used to control symptoms if required while recovery occurs. Lithium- and amiodarone-induced hypothyroidism are managed with thyroxine. The ongoing need for the lithium or amiodarone should be considered, but they can be continued if necessary.Laboratory investigation demonstrated marked TSH elevation (145 mIU/l, normal 0350 mIU/l) and low free thyroxine (39 pmol/l, normal 103232 pmol/l). Her primary care physician started thyroxine replacement at standard doses and adjusted the dosage upwards on three occasions because of persistently elevated TSH levels.