DMP1 mutations in autosomal recessive hypophosphatemia implicate a bone matrix protein in the regulation of phosphate homeostasis

Hypophosphatemia is a genetically heterogeneous disease. Here, we mapped an autosomal recessive form (designated ARHP) to chromosome 4q21 and identified homozygous mutations in DMP1 (dentin matrix protein 1), which encodes a non-collagenous bone matrix protein expressed in osteoblasts and osteocytes. Intact plasma levels of the phosphaturic protein FGF23 were clearly elevated in two of four affected individuals, providing a possible explanation for the phosphaturia and inappropriately normal 1,25(OH)2D levels and suggesting that DMP1 may regulate FGF23 expression.

Effect of methimazole, with or without L-thyroxine, on remission rates in Graves' disease

Medical treatment of Graves' disease involves antithyroid drugs with or without the addition of exogenous T4. There have been conflicting reports as to whether the addition of T4 improves remission rates or delays relapse. To evaluate this issue in a North American population, 199 patients were treated with methimazole until they were euthyroid. They were then randomized to either methimazole alone in a dose sufficient to normalize TSH (group 1), or to 30 mg methimazole daily plus sufficient T4 to maintain TSH in the upper normal range (group 2), or to 30 mg methimazole daily plus sufficient T4 to suppress TSH below 0.6 mIU/L (group 3). After 18 months, methimazole was stopped, and T4 was continued in groups 2 and 3. Because not all patients in groups 2 and 3 achieved their target TSH concentration, they were reassigned to group A (TSH > or = 1.0) or group B (TSH < 1.0), based on the mean TSH achieved during methimazole treatment. One hundred forty-nine patients have been followed for at least 6 months after stopping methimazole (mean 27 months). Fifty-eight percent of patients have relapsed. There were no significant differences in relapse rates after stopping methimazole. Among those patients who did relapse, however, there was a significant difference in the months to relapse after stopping methimazole between groups B and 1 (group 1: 3.3 +/- 0.7, group A: 5.6 +/- 0.8, group B: 7.4 +/- 1.7; P = 0.01 for the comparison between groups B and 1). We conclude that the addition of T4 to methimazole does not improve long-term remission rates in Graves' disease.

Phaeochromocytoma: a ten-year survey

We retrospectively evaluated our experience with phaeochromocytoma from January 1986 to December 1995. There were 18 patients with surgically-proven phaeochromocytoma: three males, 15 females, aged 12-81 years (mean 42 years) at diagnosis. Sixteen were hypertensive; only 6/18 presented with two or more of the classical triad of headaches, palpitations and diaphoresis. One patient presented with hypertensive crisis. Duration of symptoms prior to diagnosis was 2 weeks to 6 years, mean 16.4 months. Sixteen patients had adrenal tumours and two had extra-adrenal tumours or paragangliomas. One had bilateral adrenal tumours and two had a combination of both adrenal and extra-adrenal tumours. There were four familial cases: two had multiple endocrine neoplasia type IIA (MEN-IIA), one had neurofibromatosis type I (NF-I) and one von Hippel-Lindau (VHL) disease. One patient had Cushing's syndrome arising from ectopic production of adrenocorticotropic hormone (ACTH) by the phaeochromocytoma. Disease was recurrent in three patients. Pre-operative diagnosis was confirmed mainly by elevated urine vanillylmandelic acid (VMA) and/or catecholamine levels. Twelve patients had plasma catecholamine determinations: noradrenaline was elevated in all, adrenaline in six and dopamine in two. Pre-operative localization was by CT scan or MR imaging in all patients. At follow-up of 1-10 years (median 4.8 years), 15 patients were cured surgically while two were asymptomatic despite recurrence of disease. One patient with recurrent paragangliomas died post-operatively.

Large macroprolactinoma treated with bromocriptine alone

We report a case of a large macroprolactinoma in a 44-year-old male photographer who presented with affected colour perception and a central scotoma of the right eye. An initial computerised tomographic (CT) scan showed an enormous mass lesion extending from the nasopharyngeal area to the third ventricle, with destruction of the skull base. The initial serum prolactin level was 29 180 micrograms/L (normal < 15.8 micrograms/L) while other pituitary hormones were within normal ranges. The patient was treated with oral bromocriptine with prompt resolution of visual defects while significant reductions in tumour size (> 50%) and prolactin level (> 99%) were achieved over a one-year period. This represents one of the highest serum prolactin levels reported in the literature in a patient with a prolactin-secreting pituitary tumour and illustrates the remarkable efficacy of dopamine agonist therapy in patients with large macroprolactinomas.

Spontaneous remission of ectopic Cushing's syndrome due to pheochromocytoma: a case report

A young female adult with Cushing's syndrome arising from ectopic production of corticotropin (ACTH) from an adrenal pheochromocytoma showed spontaneous clinical and biochemical remission of hypercortisolism after a brief period of ketoconazole administration. Despite continued remission of the hypercortisolism over the next 18 months, there was progressive catecholamine hypersecretion with significant morbidity as a result of the pheochromocytoma. Surgical resection of the left adrenal gland revealed a pheochromocytoma showing focal cytoplasmic immunostaining for ACTH and marked diffuse compact cell hyperplasia in the adrenocortical tissue. To our knowledge this is the first reported case of spontaneous clinical and biochemical remission of ectopic ACTH production from a pheochromocytoma. The pathogenesis of the remission remains unknown.

Effect of methimazole with or without exogenous L-thyroxine on serum concentrations of thyrotropin (TSH) receptor antibodies in patients with Graves' disease

Medical treatment of Graves' disease involves use of antithyroid drugs with or without the addition of exogenous L-T4. There have been conflicting reports as to whether the addition of T4 reduces TSH receptor antibodies and improves remission rates more than antithyroid drugs alone. To further examine the effect of drug therapy on serum concentrations of TSH receptor antibodies. 70 patients with Graves' disease were treated with methimazole (Tapazole) alone until they were euthyroid. Then they were randomized to receive either: 1) methimazole alone in a dose sufficient to normalize TSH (0.3-5.4 mIU/L; Group 1); 2) 30 mg methimazole daily plus sufficient T4 (Synthroid) to maintain TSH in the high-normal range (2.0-5.4 mIU/L; Group 2); or 3) 30 mg methimazole daily plus sufficient T4 to suppress TSH to below 0.6 mIU/L (Group 3). The duration of treatment in all groups was 18 months. At baseline and after 6 and 18 months, TSH receptor antibodies were measured both by the ability of patients' sera to stimulate cAMP production by FRTL-5 cells (thyroid-stimulating Ig) and by the ability of patients' sera to inhibit binding of radiolabeled TSH to solubilized porcine thyroid membranes (TSH-binding, inhibiting Ig). Thyroid-stimulating Ig(TSI) and TSH-binding, inhibiting Ig(TBII) concentrations were similar among the three groups at baseline. Mean baseline TSI (expressed as the percent of normal control) for all patients combined was 306 +/- 21%. Mean baseline TBII (expressed as percent inhibition of TSH binding) was 38 +/- 2%. TSI was elevated in 85% and TBII was elevated in 75% of patients at baseline. After 18 months, TSI was elevated in 64% of patients, and TBII was elevated in 28%. Serum TSI decreased by 36 +/- 5% during the study, and there was no significant difference in the degree of reduction among the three groups (P = 0.99). Serum TBII decreased by 59 +/- 3%, and there also was no significant difference among the groups (P = 0.83). At baseline, serum TBII correlated with free T4 (r = 0.33, P < 0.01), total T3 (r = 0.55, P < 0.01), and thyroid size (r = 0.35, P < 0.01). There was no correlation between TSI and any of the baseline parameters or between TSI and TBII at any timepoint. In conclusion, we found that the addition of T4 to methimazole does not result in a greater decrease in TSH receptor antibody concentrations than treatment with methimazole alone. From these results, we would predict no difference in remission rates among these patients, but confirmation of this prediction will need to await long-term follow-up of these subjects.

Treating non-insulin-dependent diabetes. Oral agents or insulin?

This article describes suggested treatment regimens for non-insulin-dependent diabetes mellitus. Diet is usually the first-line therapy. If this fails, most patients should be given a trial of oral agents, usually sulfonylurea first. Sulfonylurea and metformin can be combined if necessary. If oral agents fail, insulin is indicated. Insulin and an oral agent sometimes are used together.

Thyroid tests: guide for primary care physicians

Recent advances in thyroid testing have simplified the approach to the screening and diagnosis of thyroid disorders. The metabolic state is best determined by the serum free thyroxine and a sensitive assay for serum thyroid-stimulating hormone. The presence and nature of a goitre is assessed by clinical examination and, in the case of nodular thyroid disease, this examination can be supplemented by pertechnetate isotope scanning, ultrasonography, or fine needle aspiration biopsy. In most patients, these tests will identify the presence of and provide a guide to the diagnosis of thyroid disease. There is little need for radioactive iodine studies for diagnostic purposes.

Cerebrospinal fluid rhinorrhea caused by bromocriptine therapy of prolactinoma

We studied a man with cerebrospinal fluid rhinorrhea due to bromocriptine-induced shrinkage of a prolactin-secreting pituitary tumor. Unlike other reported cases with pituitary tumors and rhinorrhea, our patient never had previous radiotherapy or surgery. The fistula was clearly demonstrated by CT. The original signs included homonymous hemianopia due to a left optic tract compression. Bromocriptine treatment is an invaluable adjunct in long-term management of invasive prolactinomas, but surgical intervention is indicated if a CSF fistula results.

Serum thyroglobulin in the diagnosis and management of thyroid carcinoma

Serum thyroglobulin (Tg) was measured by radioimmunoassay in sixty-two control subjects, 163 euthyroid patients with nodular goitre and eighty-one patients with previously treated differentiated thyroid carcinoma. Tg was elevated in 65% of nodular goitres and failed to fall with thyroxine treatment in ten/fifteen patients treated. A diagnosis of differentiated carcinoma was confirmed in fourteen/sixty-four of these patients and Tg was elevated in twelve. Of sixty-five treated thyroid carcinoma patients without evidence of residual tumour, serum Tg was undetectable in thirty-nine, normal in twenty-four and elevated in two. There was evidence of residual tissue in the thyroid in seventeen of the patients with detectable Tg. Of the sixteen patients with residual tumour or metastases Tg was elevated in fifteen. There was a positive correlation between goitre size and Tg levels in multinodular goitre, and thyroid carcinomas of large bulk were associated with higher Tg levels. Serum Tg was normal in medullary carcinoma and in two patients with thyroid metastases from extra-thyroidal malignancies. High Tg levels in patients with residual metastases from thyroid carcinoma following thyroid ablation indicates Tg production by tumour tissue. Measurement of serum Tg of limited value in the differential diagnosis of nodular thyroid disease. It is particularly useful following surgery and 131I therapy for differentiated thyroid carcinoma. In these patients it gives confirmation of thyroid albation and may provide evidence of residual tumour tissue when the other tests are negative.

Amino acid incorporation by a cell-free preparation from rat adipose tissue. Effects of fasting

Ribosomes were isolated from a postmitochondrial, detergent-treated supernatant fraction prepared either from adipose tissue passed through a tissue press, or from a collection of free fat cells. Optimum conditions for incorporation were established and the kinetics of the system denned with and without artificial messenger RNA. Studies were performed on ribosomes isolated from fed, 24-h fasted, and 48-h fasted animals. There was a progressive reduction in yield and activity (per milligram ribosomal RNA) of ribosomal material recovered from animals fasted up to 48 h. In the presence of poly-U, incorporation by ribosomes from fasted animals returned towards but did not reach the fed level. This return was less complete with ribosomes from 48-h than from 24-h fasted groups although as fasting proceeded, the percentage stimulation produced by poly-U progressively increased. Sucrose density gradient analysis revealed a greater proportion of light ribosome species and a smaller proportion of polysomes in fasted than in fed animals. These results suggest that fasting, in addition to producing a progressive reduction in ribosomal yield, also caused an early loss of messenger RNA or messenger function and later an alteration of ribosome function. The effect of fasting on messenger function could not be explained by alterations in ribonuclease activity.