Heres the text of the article:
Hypothyroidism in Thyroid Carcinoma Follow-up: Orlistat
May Inhibit the Absorption of Thyroxine
Sir d Orlistat is used in the management of obesity to reduce the
absorption of fat. Thyroxine is used in the management of welldifferentiated
thyroid cancer to suppress thyroid-stimulating hormone
(TSH) production. We report a case of symptomatic hypothyroidism
occurring after the commencement of orlistat in a patient with papillary
carcinoma of the thyroid.
After total thyroidectomy and radio-iodine ablation, suppression of
TSH by the anterior pituitary is part of the standard management
of differentiated thyroid cancer . Doses of thyroxine in the order of
175–200 mg are commonly required to produce adequate suppression
. Orlistat is a recently licenced drug used in obesity management.
Orlistat promotes weight loss by reducing the absorption of energy
dense fat. It is a potent inhibitor of pancreatic and gastric lipases,
allowing about 30% of dietary fat to pass through the gastrointestinal
tract unabsorbed .
A 46-year-old woman was diagnosed in August 2002 with papillary
carcinoma of the thyroid. After completing thyroidectomy in September
2002, and radio-active iodine (I131 3000 MBq) ablation therapy in
December 2002, she was commenced on 250 mg of thyroxine daily.
Thyroid function tests carried out in May 2004 revealed serum thyroxine
(T4) level of 25.2 pmol/L and TSH 0.03 mU/L, indicating nearly adequate
suppression of TSH.
In June 2004, she was commenced on orlistat by her general
practitioner. Within 2 weeks, she experienced hypothyroid symptoms in
the form of tiredness, lethargy and cold intolerance. Biochemically, she
was found to be profoundly hypothyroid with T4 7 pmol/L and TSH
73.6 mU/L. During this period, the patient’s husband witnessed good
compliance with medication.
The woman was advised to discontinue orlistat, and her thyroxine was
increased to 300 mcu once daily. Within 2 weeks, her symptoms improved.
Repeat blood tests carried out 4 weeks later showed TSH 0.02 mU/L and
T4 31.7 pmol/L.
Causes of inadequate TSH suppression include inadequate thyroxine
dose due to poor patient compliance or reduction to a replacement dose by
the general practitioner. Clear communication of the rationale behind TSH
suppression is therefore essential. In this case, the patient had been
compliant with thyroxine for 18 months as indicated by her previous
biochemistry, and both the patient and her husband were adamant that she
had continued to comply.
Orlistat has been associated with gastrointestinal adverse events,
including diarrhoea, constipation, abdominal pain and flatulence. In
addition, orlistat is known to cause malabsorption of fat soluble vitamins,
hypocalcaemia, and, rarely, other electrolyte disturbances. Thyroid
dysfunction is very rare .
Thyroxine has a bioavailability of 40–80% after oral administration. The
extent of thyroxine absorption is increased in the fasting state, and is
influenced by the content of the gastrointestinal tract. Some substances
bind the thyroxine, making it unavailable for diffusion across the gut wall
. It may be that orlistat also binds to the thyroxine and prevents its
absorption from the small intestine.
We believe that this is the first reported case of hypothyroidsm in
a patient taking TSH suppressive dose of both thyroxine and orlistat. It is
clearly important that clinical oncologists, thyroid surgeons, endocrinologists
and general practitioners involved in the follow-up of thyroid cancer
patients are aware of this potential interference of this drug with thyroxine
Queen Elizabeth Hospital, Birmingham, UK
1 Halnan KE. Thyroid. In: Price P, Sikora K, eds. Treatment of cancer.
London: Chapman and Hall, 1995. p. 367–390.
2 Guidelines for the management of thyroid cancer in adults. British
Thyroid Association, Royal College of Physicians; March 2002.
3 Hollander PA, Elbein SC, Hirsch IB, et al. Role of orlistat in the
treatment of obese patients with type 2 diabetes. A 1-year randomized
controlled study. Diabetes Care 1998;21:1288–1294.
4 Mc Duffie JR, Calis KA, Booth SL, Uwaifo GI, Yanovski JA. Effects of
orlistat on fat soluble vitamins in obese adolescents. Pharmacotherapy
5 Roberts G. Taking care of thyroxine. Aust Prescr 2004;27:75–76.
Hair Growth After Gefitinib Treatment
Sir d We report an interesting case of new hair growth after gefitinib
treatment. A 57-year-old man with androgenic alopecia first presented with
back pain in January 2004. A bone scan showed increased uptake in
the sacrum, and the lumbar spine. A biopsy of the spine confirmed
adenocarcinoma consistent with non-small-cell lung cancer. A computed
Fig. 1 – New hair growth on previous bald vertex.
Clinical Oncology (2005) 17: 492–493
0936-6555/05/000000C02 $35.00/0 2005 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.