An unusual cause of acromegaly.

We report a rare case of acromegaly due to a growth hormone releasing hormone-secreting bronchial carcinoid tumour. A 40-year-old man initially presented with acromegalic features, and was subsequently found to have a large lung mass in the right lower zone on chest X-ray. Right lower lobectomy was performed, and the tumour was confirmed to be a bronchial carcinoid tumour on histology. Resection of the tumour led to normalisation of serum insulin-like growth factor 1 level and growth hormone responses to an oral glucose tolerance test.

Review on the use of insulin in primary care.

Diabetes mellitus is one of the major causes of premature morbidity and mortality. Studies show that intensive glycaemic control could significantly reduce the risk of diabetic complications. With the increasing number of diabetic patients under primary care indicated for insulin, family physicians will play a pivotal role in prescribing it in their setting. The initiation and titration of any insulin regimen is not difficult in most patients. With support from diabetes nurses and training on insulin use, family physicians can provide insulin therapy to diabetic patients in the community and reduce the number of referrals to secondary care. This article reviews the most updated clinical guidelines on insulin use to better equip family physicians on the initiation and titration of insulin in primary care.

Usage of a fixed dose of radioactive iodine for the treatment of hyperthyroidism: one-year outcome in a regional hospital in Hong Kong.

OBJECTIVES: To evaluate the efficacy of a fixed dose of radioactive iodine (131-I) in the treatment of thyrotoxicosis, and to identify risk factors associated with treatment failure. DESIGN: Retrospective study. SETTING: Thyroid Clinic of a regional hospital in Hong Kong. PATIENTS: Patients receiving their first dose of radioactive iodine for the treatment of thyrotoxicosis during the inclusive period September 1999 to August 2004. MAIN OUTCOME MEASURES: Relapse rate and time to relapse. RESULTS: A total of 113 patients received a fixed dose of 5 mCi (185 MBq), 6 mCi (222 MBq), 8 mCi (296 MBq), and 10 mCi (370 MBq) 131-I in a proportion of 1:6:71:35. At 1 year, 42 (37%) of the patients had relapsed, of which 69% received a second 131-I dose. The median time to relapse after first receiving 131-I was 4 months. At 1 year, the remaining 71 (63%) of the patients were successfully treated; 46 (41%) were euthyroid, and 25 (22%) had became permanently hypothyroid. Basal free thyroxine level and goitre size were significantly associated with a relapse rate after a single dose of 131-I; larger goitres showed a trend towards high rates of relapse. Patients pretreated with propylthiouracil had a higher rate of relapse during the first year after radioactive iodine than those pretreated with carbimazole, but the difference was not significant when combined with other pretreatment variables. CONCLUSIONS: A single fixed dose of radioactive iodine is a simple, safe, and effective treatment for hyperthyroidism. High basal free thyroxine concentration and large goitre size are associated with higher chance of relapse. Higher radioiodine doses may be considered to improve the cure rate.

Five new families with resistance to thyroid hormone not caused by mutations in the thyroid hormone receptor beta gene.

Resistance to thyroid hormone (RTH) is a syndrome of variable tissue hyposensitivity to TH. In 191 families, the RTH phenotype has been linked to mutations located in the ligand-binding or hinge domains of the TH receptor (TR) beta gene. The defective TRbeta molecules interfere with the function of the normal TRs to produce dominantly inherited RTH. Of the 65 families with RTH studied in our laboratory, 59 had mutations in the mutagenic region of the TRbeta gene that encompasses exons 7-10. Isolation of a TRbeta PAC (P1 derived artificial chromosome) clone provided the intronic sequences necessary to amplify and sequence the entire TRbeta gene from genomic DNA. Not a single nucleotide substitution, deletion, or insertion was found in all coding and noncoding TRbeta1- and TRbeta2-specific and common exons of the five families with RTH reported herein. Furthermore, linkage analysis using polymorphic markers excluded involvement of the TRbeta and TRalpha genes in two and three of the five families, respectively. The phenotype of RTH in patients without TRbeta gene defects was not different from that in patients with RTH due to TRbeta gene mutations in terms of clinical presentation and reduced responsiveness of the pituitary and peripheral tissues to TH. However, the degree of thyrotroph hyposensitivity to TH appeared to be among the more severe, similar to that of patients with mutant TRbetas that have more than 50-fold reduction of T3 binding affinity and strong dominant negative effect. In these five families and another with non-TRalpha/non-TRbeta RTH, previously identified in our laboratory, evidence for dominant inheritance was secured in two families, and the appearance of a new defect or recessive inheritance was found in the remaining four families. RTH without a structural TRbeta defect occurs in about 10% of families expressing the classic phenotype of TH hyposensitivity, and TRbeta and TRalpha gene involvement has been excluded in 5%. We postulate that a cofactor that interacts with TR is potentially responsible for the manifestation of RTH in these families. As affected subjects are not infertile, the high prevalence of putative neomutations and the low rate of transmission in this non-TR form of RTH may be due to reduced survival of embryos harboring the defect.

Does insulin therapy have a hypertensive effect in type 2 diabetes?

In this prospective study, the 24-h blood-pressure profile of 12 patients with type 2 diabetes was monitored before, at 6, and at 12 weeks after initiation of insulin therapy, to determine whether commencement of insulin therapy increases blood pressure in these patients. Insulin dosage adjustment was carried out by using a predetermined algorithm according to body weight and degree of hyperglycemia. The mean insulin dosage at 12 weeks was 72.9 +/- 3.9 units/day. This was associated with an increase in systolic blood pressure from 134.6 +/- 4.3 mm Hg to 144.8 +/- 4.5 mm Hg (p = 0.0001), diastolic blood pressure from 71.9 +/- 2.6 mm Hg to 74.9 +/- 2.2 mm Hg (p = 0.0001), and body mass index (BMI) from 27.2 +/- 0.8 kg/m2 to 29.6 +/- 0.8 kg/m2 (p = 0.0001). Multiple regression analysis showed insulin dosage to be a significant independent factor (p = 0.0003) accounting for 63% of the variance in blood pressure change after adjusting for age, diastolic blood pressure, and base HbA1c. We conclude that insulin therapy may have a deleterious effect on blood pressure in patients with type 2 diabetes. However, in the clinical setting, it is difficult to isolate this from the confounding effect of weight gain.