Primary hypothyroidism

• Adults < 65yrs with no history of CVD: Levothyroxine 1.6 mcg/kg  day (rounded to the nearest 25 mcg), Repeat TSH every 2-3 months and increase by 25-50µg unti euthyroid
• Adults > 65yrs and adults with a history of CVD: Levothyroxine 25–50 micrograms once daily; adjusted in steps of 25 micrograms every 4 weeks, adjusted according to response; maintenance 50–200 micrograms once daily

Levothyroxine 

•  Take 30–60 minutes before breakfast, caffeine-containing liquids (e.g. coffee, tea), or other medication.
• Interactions
  • Iron supplements, including multivitamins that contain iron
  • Cholestyramine (Prevalite), a medication used to lower blood cholesterol levels
  • Aluminum hydroxide, which is found in some antacids
  • Sucralfate, an ulcer medication
  • Calcium supplements
  • proton pump inhibitors
  • oral contraceptives
  • anti-epileptic medication (such as carbamazepine and phenytoin)
  • some antibiotics (such as rifampicin)
  • raloxifene
• Absorbtion can be reduced by
  • coeliac disease
  • Helicobacter pylori-related gastritis
  • atrophic gastritis/pernicious anaemia
  • inflammatory bowel disease
• Absorbtion can be reduced by  
  • soya products
  • high-fiber diet
  • milk
  • coffee
  • papaya
• Cautions
  • Cardiac - In elderly patients and patients with with ischaemic heart disease start with 25µg and increase in 25µg increments 
  • Diabetes - may need to increase antidiabetic drugs
  • Hypertension
  • Elderly

Tri-iodothyronine  

• T4 is of no value in patients on tri-iodothyronine replacement and T3 is of limited value because of the variability after taking the replacement dose. TSH is required to optimise tri-iodothyronine replacement therapy
• TSH - suppression of TSH may result in cardiac problems or bone loss. Therefore, it is recommended that a reduction in thyroxine dose is made to bring the TSH within the reference range

Liothyronine and natural thyroid extract

There is not enough evidence that it offers benefits over levothyroxine, and the long-term adverse effects are uncertain Laura to write 

Monitoring

• Measure T4 as well as TSH for adults who continue to have symptoms of hypothyroidism after starting levothyroxine
• Aim for T4 in the upper half of the reference range and TSH normal
• Then measure TSH annually 
• Note: TSH may remeain suppressed for upto 6 months and aim for around 2mU/L

Conditions associated with thyroid disfunction

• Atrial Fibrillation
• Hyperlipidaemia 
• Osteoporosis
• Subfertility
• Diabetes 
• Down Syndrome and Turner’s Syndrome
• TSH should be measured annually in these patients 

Normal ranges for children

Age	Free T4* (ng/dL)	T4 (mcg/dL)	TSH (mU/L)
Cord blood	0.9 to 2.2	7.8 to 13.1	2.2 to 10.7
1 to 4 days	2.2 to 5.3	9.3 to 20.9	2.7 to 26.5
4 to 30 days	0.9 to 3.4	8.0 to 21.8	1.2 to 13.1
1 to 12 months	0.9 to 2.3	7.2 to 15.7	0.6 to 7.3
1 to 5 years	0.8 to 1.8	6.4 to 13.5	0.7 to 6.6
6 to 10 years	1.0 to 2.1	6.0 to 12.8	0.8 to 6.0
11 to 18 years	0.8 to 1.9	4.7 to 12.4	0.6 to 5.8
>18 years	0.9 to 2.5	5.3 to 10.5	0.4 to 4.2

Monitoring after Radioactive iodine treatment

• Consider measuring TSH, FT4 and FT3 levels in adults, children and young people every 6 weeks for the first 6 months after radioactive iodine treatment until TSH is within the reference range
• For adults, children and young people who have hypothyroidism after radioactive iodine treatment and are not on antithyroid drugs, offer levothyroxine replacement therapy and follow recommendations made in Managing primary hypothyroidism on dosage of levothyroxine for adults and in Tests for follow-up and monitoring of primary hypothyroidism on monitoring of hypothyroidism
• For adults, children and young people with TSH in the reference range 6 months after radioactive iodine treatment, consider measuring TSH (with cascading) at 9 months and 12 months after treatment
• For adults, children and young people with TSH in the reference range 12 months after radioactive iodine treatment, consider measuring TSH (with cascading) every 6 months unless they develop hypothyroidism (then follow the recommendation above)
• If hyperthyroidism persists after radioactive iodine treatment in adults, children and young people, consider antithyroid drugs^[2] until the 6-month appointment
• If hyperthyroidism persists 6 months after radioactive iodine treatment in adults, children and young people, consider further treatment

Monitoring after surgery

• Offer levothyroxine to adults, children and young people after a total thyroidectomy and follow recommendations on dosage of levothyroxine for adults and on monitoring of hypothyroidism
• Consider measuring TSH and FT4 at 2 and 6 months after surgery, and then TSH (with cascading) once a year for adults, children and young people who have had a hemithyroidectomy

Monitoring after stopping antithyroid drugs

• TSH (with cascading) within 8 weeks of stopping the drug, then
• TSH (with cascading) every 3 months for a year, then
• TSH (with cascading) once a year

Hyperthyroidism

• Carbimazole
  • 15–40 mg daily until euthyroid, then reduced gradually to 5–15 mg daily
  • Monitor after 4 to 8 weeks
  • higher doses should be prescribed under specialist supervision only
  • therapy usually given for 12 to 18 months.
• Propylthiouracil
  • 200-400mg daily in divided doses until patient becomes euthyroid then reduce to 50-150mg daily in divided doses
  • Monitor after 4 to 8 weeks

Agranulocytosis/Neutropaenia

Rare side effect of carbimazole and propylthiouracil

If patient has a severe soar throuat or mouth

Subclinical hyperthyroidism

• Consider seeking specialist advice on managing subclinical hyperthyroidism in adults if they have:
  • 2 TSH readings lower than 0.1 mIU/litre at least 3 months apart and
  • evidence of thyroid disease (for example, a goitre or positive thyroid antibodies) or symptoms of thyrotoxicosis
• Consider seeking specialist advice on managing subclinical hyperthyroidism in all children and young people

Monitoring

• Consider measuring TSH every 6 months for adults with untreated subclinical hyperthyroidism. If the TSH level is outside the reference range, consider measuring FT4 and FT3 in the same sample
• Consider measuring TSH, FT4 and FT3 every 3 months for children and young people with untreated subclinical hyperthyroidism
• Consider stopping TSH measurement for adults, children and young people with untreated subclinical hyperthyroidism if the TSH level stabilises (2 similar measurements within the reference range 3 to 6 months apart)

 Diagnosis

• If the serum TSH concentration is within the reference range then a diagnosis of hyperthyroidism is effectively ruled out
• Measure thyroid peroxidase antibodies (TPOAbs) for adults with TSH levels above the reference range, but do not repeat TPOAbs testing

Diagnosis	TSH	T4	Action
Primary Hypothyroidism	>10mU/L	low	Levothyroxine 1.6 mcg/kg  day (rounded to the nearest 25 mcg) for adults under 65 with no history of cardiovascular disease Levothyroxine 25 to 50 mcg/day with titration for adults aged 65 and over and adults with a history of cardiovascular disease
Subclinical (mild) hypothyroidism	>10mU/L	normal	repeat TSH after 3-6 months take into account features that might suggest underlying thyroid disease, such as previous thyroid surgery or raised levels of thyroid autoantibodies. Consider levothyroxine for adults with subclinical hypothyroidism who have a TSH of 10 mlU/litre or higher on 2 separate occasions 3 months apart.
Secondary hypothyroidism	Low	Low	After a full diagnosis has been made and steroid treatment initiated, thyroxine should be given in increasing 25µg doses and optimised such that the thyroid hormone concentration is within the upper third of the reference range
	High but <10mU/L		Repeat the measurement within one to two months If the repeat serum TSH measurement remains low but >0.1mU/L with normal FT4 and/or FT3, then repeat testing every 6-12 months is required thyroid peroxidase antibodies (TPA) should be measured if TPA high then TSH should be measured annually or earlier if symptoms develop If TPA not raised, repeat measurement of serum TSH approximately every three years
	Low but >0.1mU/L		repeat after 1-2 months
	Low < 0.1mU/L		Measure T4 and T3 to exclude overt hyperthyroidism. If treatment is not undertaken, repeat TSH every 6-12 months, with follow-up measurements of serum T4 and T3 if the serum TSH result is low
Graves disease	Low	High	Carbimazole for 12 to 18 months, using either a block and replace or a titration regimen, and then review the need for further treatment.  Propylthiuracil 200-400mg daily in divided doses until patient becomes euthyroid then reduce to 50-150mg daily in divided disease for: adverse reactions to carbimazole pregnant or trying to become pregnant within the following 6 months history of pancreatitis.
Hashimoto's  disease an autoimmune disorder that can cause hypothyroidism immune system attacks the thyroid	When the thyroid begins to fail, the pituitary gland makes more TSH to trigger the thyroid to make more thyroid hormone. When the damaged thyroid can no longer keep up, thyroid hormone levels drop below normal.	T4 low	An antibody test tells whether patiemnt has the antibodies that suggest Hashimoto’s disease. More than one in 10 people have the antibodies but have normal thyroid function. Having only the antibodies does not cause hypothyroidism.

 

Pregnancy

Planning a pregnancy

• Check thyroid function before conception
  • If TFTs are not within the euthyroid range, advise delaying conception, until stabilised on levothyroxine treatment
• Check that the woman understands that her dose of levothyroxine must be adjusted as early as possible in pregnancy to reduce the chance of obstetric and neonatal dammage

Hypothyroidism 

• Patients with established hypothyroidism should have levothyroxine dose increased by 25 micrograms as soon as a positive pregnancy test is found
• Check thyroid function after 2 weeks 
•  Aim for
  • T4 16-21 pmol/L
  • TSH <2 mU/L
• Refer to an endocrinology specialist all women with overt or subclinical hypothyroidism is this correct?
• Check thyroid function every trimester
• Cut back T4 dose to pre-pregnancy dose 2-6 weeks post-partum 

Hyperthyroidism

• Refer all women with hyperthyroidism in pregnancy to endocrinologist is this correct?
• Measure TRAbs in all patients with Graves disease
• Patients with detectable TRAbs require special management, irrespective of their thyroid function test profile.
• The aim is for good control of hyperthyroidism on the minimum dose of carbimazole / propylthiouracil possible