Evaluation of sephadex column methods for the estimation of total serum thyroxine level and triiodothyronine resin uptake

A new mutation in the growth hormone-releasing hormone receptor gene in two Israeli Arab families

BACKGROUND

Mutations in the GHRH receptor gene (GHRH-R) are emerging as a common cause of familial isolated GH deficiency (IGHD).

DESIGN

We searched for GHRH-R mutations in 10 patients with IGHD of Israeli-Arab origin, belonging to two highly consanguineous families.

METHODS

Analysis of the 13 coding exons, the intron-exon boundaries, and the proximal promoter of the GHRH-R was performed by denaturing gradient gel electrophoresis. Abnormally migrating bands were sequenced. The newly found mutation was inserted into GHRH-R cDNA. Wild type and mutant receptor were expressed in Chinese hamster ovary (CHO) cells, and the cAMP response to GHRH was measured.

RESULTS

All patients were homozygous for a novel GHRH-R missense mutation in exon 11 that replaces arginine with cysteine (R357C). Functional assay demonstrated complete inactivity of the mutant receptor in vitro. The prevalence of the mutant allele in the Israeli-Arab population was found to be 2%. All the patients had low but detectable GH reserve, proportionate short stature, and growth retardation since early childhood, with good growth response to GH treatment. Magnetic resonance imaging, performed in 3 patients, revealed a normal sized anterior pituitary in one patient evaluated at early childhood, and a borderline hypoplastic gland in the 2 patients evaluated at puberty.

CONCLUSIONS

We describe a novel missense mutation in the GHRH-R. The high incidence of the mutant allele in Israeli Arabs suggests that the mutation may be a common cause of familial IGHD in this population.

Growth without growth hormone: growth pattern and final height of five patients with idiopathic combined pituitary hormone deficiency

BACKGROUND

Growth without GH has been reported in patients with organic combined pituitary hormone deficiency (CPHD) after resection of craniopharyngiomas and hypothalamic tumours or in septo-optic dysplasia.

METHODS

This study describes the growth pattern and final height of five children (four boys, one girl) with idiopathic CPHD (GH, TSH, ACTH, LH and FSH) who maintained normal growth despite persistent GH deficiency throughout the growth period.

RESULTS

Presenting findings were borderline small penis in two children diagnosed at ages 3 and 9 years, and absence of pubertal signs in three adolescents diagnosed at age 12.8-13.7 years. The latter three patients also exhibited acromegaloid features. The height of all patients was within the 10-25th percentiles, and weight at the 25-50th percentiles. Although they were moderately overweight, accelerated weight gain was not observed. Prepubertal growth rate was 4-5 cm/year. The pubertal growth period, starting after initiation of sex hormone therapy (chronological age 15.9-16.3 years and bone age 12.5-14.5 years) continued for 4-5.5 years. Total pubertal growth was 6-11.7 cm with reduced growth spurt. Final height, which was attained at an advanced age (19-22 years), was 170-179 cm in the boys and 164 cm in the girl, equal to or exceeding the target height range. Repeated hormonal evaluations revealed undetectable GH and IGF-I levels, and no evidence of hyperprolactinaemia or hyperinsulinism.

CONCLUSIONS

Final height attainment within or above target height range may occur in patients with idiopathic CPHD despite persistent GHD. As this was not mediated by GH, IGF-I, insulin or prolactin, some other growth factors probably played a growth-promoting role.

The TRH test in normal subjects: methodological considerations

Changes in serum TSH, PRL, GH, T3, T4 and FT4-Index after injection of TRH (500 micrograms i.v.) were measured in 13 normal women and 12 normal men. In both sexes, TSH and PRL concentrations rose significantly over baseline after TRH injection (p less than 0.01). The PRL response, but not the TSH response, was significantly lower in men than in women. Although most TSH and PRL peaks occurred about 30 min after TRH injection, a delayed PRL peak was seen in four men. Thyroid hormones also rose significantly after TRH, with T3 peaking earlier (60 min) than T4 and FT4-Index (greater than or equal to 180 min). The TSH area under the curve correlated well with the TSH peak value (p less than 0.001), with the TSH value at 30 min (p less than 0.001), with the delta max TSH (p less than 0.001), and with the delta TSH measured at 30 min (delta 30 TSH) (p less than 0.001). The PRL area under the curve correlated well with the PRL peak value (p less than 0.005) and with delta max PRL (p less than 0.05) in both sexes, but the PRL value at 30 min was significantly correlated with the area under the curve only in women (p less than 0.005). These data indicate that in both sexes a baseline sample and a 30-min sample provide an excellent index of the entire TSH secretory response to TRH; the PRL response to TRH is clearly related to sex; and the 30-min value of PRL in women, but not in men, is an adequate measure of the PRL secretory response to TRH.

The TRH test during dopamine receptor blockade in depressed patients

In an evaluation of the possible role of dopamine on TRH test results, 21 depressed patients were given TRH before and after one week of treatment with a low dose of haloperidol. Haloperidol significantly increased serum prolactin (both basal and after TRH) and cortisol levels, decreased body temperature, and had no effect on serum TSH, growth hormone, or thyroid hormone levels. Five of six patients with initial TSH blunting were retested with TRH; in four patients the TSH response remained blunted. These data render it unlikely that dopamine exerts a major inhibitory input on TSH secretion in depression.

The TRH test in patients wih borderline personality disorder

Fifteen patients with a primary diagnosis of borderline personality disorder were studied with the thyrotropin-releasing hormone (TRH) test. Twelve carried the additional diagnosis of depression, substance abuse, or both. A blunted thyroid-stimulating hormone (TSH) response to TRH was found in seven patients, two of whom were neither depressed nor had the additional diagnosis of depression and/or substance abuse. TSH blunting was unrelated to such factors as thyroid status, serum cortisol, weight, height, or body surface. Since TSH blunting occurs in about 25% of patients with major depression but not in schizophrenia, the findings suggest that some patients with borderline personality disorder share a neuroendocrine abnormality with some affective disorder patients.

Endocrine and behavioral changes in depression after thyrotropin-releasing hormone (TRH). Alteration by pretreatment with thyroid hormones

The effects of pretreatment with a single dose of thyroid hormones (TH) on the subsequent endocrine and behavioral response to TRH was evaluated in unipolar depressed women. TH pretreatment altered neither serum levels of thyroid hormones nor the TRH-induced TSH response. It antagonized, however, the behavioral response to TRH. This was apparent in 2 self-assessment scales but not in an objective rating scale. Taken together the data suggest that (a) there is an impaired pituitary response to TH feedback in depressed patients; (b) TH pretreatment may affect self-assessment of behavioral effects of TRH in depression.

Psychological and thyroid-stimulating hormone changes after thyrotropin-releasing hormone in normal women: antagonism by pretreatment with thyroid hormones

In a double-blind crossover design we treated 20 normal women with thyrotropin-releasing hormone (TRH), 0.5 mg i.v., and saline in a random sequence. Both injections were preceded, 48 hours before, by a single dose of oral thyroid hormones (TH). TRH caused a shift toward mild euphoria, both on objective and subjective ratings. Although statistically significant, the effect was less than that observed in a previous study of normal women in which TH pretreatment was not used. Thus, TH pretreatment appeared partly to block psychological response to TRH. As expected, TH pretreatment also partly blocked thyroid-stimulating hormone (TSH) responses to TRH. Nevertheless, just as in our previous study, psychological responses were significantly negatively correlated with TSH responses. TH appears to exert two independent negative feedback effects: one on the brain (dimished psychological response); and one on the anterior pituitary (diminished TSH response).

Ectopic thyroid gland. A clinical study of 30 children and review

Of 108 children being treated at our Institute for primary (nongoitrous) hypothyroidism, tests with radioactive iodine 131I uptake showed that 26 of them (24%) had an ectopic thyroid gland. Four euthyroid children also had anterior swellings of the neck which, in each case, proved to be an ectopic thyroid gland. Of the 30 children studied, 20 were girls and 10 were boys. Nine patients were diagnosed within the first year of life. Growth retardation, manifest in 20 patients, was the most common clinical finding at the time of diagnosis. Delayed bone age was a feature in all of them. Growth, after diagnosis was within normal limits in 83% of the infants who were treated within the first two years of life; only 50% of the children diagnosed later grew within normal limits. Similarly, mental function was best preserved in those patients in whom treatment was initiated within the first two years of life.

Anaesthesia for thyroid surgery

The principles involved in preoperative assessment and management of the patient who is to undergo thyroidectomy are discussed.

The techniques of anaesthesia that have been found most successful for thyroidectomy at The Royal North Shore Hospital of Sydney are described. The effectiveness of these techniques is indicated by reference to the complications found following review of 200 consecutive thyroidectomies.