SummaryPhaeochromocytoma crisis is an endocrine emergency associated with significant mortality. There is little published guidance on the management of phaeochromocytoma crisis. This clinical practice update summarizes the relevant published literature, including a detailed review of cases published in the past 5 years, and a proposed classification system. We review the recommended management of phaeochromocytoma crisis including the use of alpha-blockade, which is strongly associated with survival of a crisis. Mechanical circulatory supportive therapy (including intra-aortic balloon pump or extra-corporeal membrane oxygenation) is strongly recommended for patients with sustained hypotension. Surgical intervention should be deferred until medical stabilization is achieved.

No abstract

The thyroid target Ag for disease-inducing autoantibodies in Graves’ disease is the receptor for thyroid-stimulating hormone (TSH), but little is known about the molecular basis of this pathogenic Ab response. We describe the characteristics of two high- affinity mAbs developed from an experimental murine model of hyperthyroid Graves’ disease that exhibit potent thyroid-stimulating activity. Nanogram concentrations of the IgG mAbs KSAb1 and KSAb2 and their Fab induce full stimulation of the TSH receptor that is matched by the ligand TSH and, thus, act as full agonists for the receptor. However, KSAb1 and KSAb2 display differential activities in their ability to block TSH-mediated stimulation of the receptor, indicating subtle differences in their biological properties. In displacement studies, IgG and Fabs of KSAb1 and KSAb2 compete with Graves’ disease autoantibodies as well as thyroid-blocking Abs present in some hypothyroid patients, indicating a close relationship between these autoimmune determinants on the receptor. In passive transfer studies, single injections of microgram quantities of KSAb1 or KSAb2 IgG led to rapid elevation of serum thyroxine and a hyperthyroid state that was maintained for a number of days. The thyroid glands showed evidence of cell necrosis, but there was no accompanying mononuclear cell infiltrate. In studying their receptor activation pathways, both KSAb1 and KSAb2 provoked phosphorylation of the intracellular ERK1/2 pathway in primary thyrocytes, indicating that multiple signaling pathways may participate in the pathogenesis of Graves’ disease. In summary, our findings emphasize the similarities of the experimental mouse model in reproducing the human disorder and provide improved means for characterizing the molecular basis of this pathogenic response.

Microsomal antibodies and antibodies directed toward the receptor for thyroid-stimulating hormone (TSH) decreased in parallel while patients with Graves' disease were taking carbimazole, whereas no significant changes were observed during treatment with placebo or propranolol. The changes in autoantibody levels during carbimazole treatment were independent of changes in serum thyroxine and could have been due to a direct effect of the drug on autoantibody synthesis. Evidence for this suggestion was provided when low doses of methimazole (the active metabolite of carbimazole) were found to inhibit thyroid-autoantibody production in cultured lymphocytes. Since thyroid lymphocytes are probably a major site of thyroid-antibody synthesis in Graves' disease and methimazole is concentrated in the thyroid during treatment, a local action of the drug on antibody production seems likely. This possibility could be important in the use of carbimazole to control hyperthyroidism.

These findings support animal work suggesting that hypothyroidism reduces central 5-HT activity. They also suggest a threshold effect in that higher TSH levels predicted both lower 5-HT mediated endocrine responses and the presence of clinical depression.

No abstract

A high prevalence of postpartum thyroid dysfunction has been reported in several countries, but there have been no systematic studies of its prevalence in Britain. Among a group of 901 consecutive, unselected pregnant women thyroid autoantibodies were detected in 117 (13%) at booking. The clinical course of postpartum thyroid dysfunction, factors associated with its development, and its likely prevalence were defined in 100 of these women with thyroid antibodies and 120 women with no such antibodies who were matched for age. None of the women had a history of autoimmune thyroid disease. Normal reference ranges for thyroid function during pregnancy and post partum were established in the 120 women negative for thyroid antibodies. On the basis of these observations postpartum thyroid dysfunction was observed in 49 (22%) of the 220 women studied, and the prevalence in the total group of901 women was estimated to be 16.7%. Thyroid dysfunction, mainly occurring in the first six months post partum, was usualiy transient and included both destruction induced hyperthyroidism and hypothyroidism. The development ofthe syndrome was significantly related to smoking more than 20 cigarettes a day and the presence of thyroid microsomal autoantibodies at booking. Of the 16 women with a family history of thyroid disease in whom thyroid microsomal autoantibody activity was detectable at booking, 11 developed thyroid dysfunction. Age, parity, presence of goitre at presentation, duration of breast feeding, and the sex and birth weight of

We have characterized four murine monoclonal antibodies (mAbs) to the extracellular domain of the human TSH receptor (TSH-R.E), the target autoantigen of Graves' disease. Recombinant TSH-R.E used as immunogen, was produced in E. coli as a fusion protein with glutathione-S-transferase or in a baculovirus-insect cell system, as a non-fusion glycoprotein. To increase the epitope specificity of the mAbs, two different strains of mice (H-2(b) and H-2(d)) were immunized. The epitopes recognized by the mAbs were characterized by immunoblotting with various recombinant constructs of TSH-R.E and by binding to overlapping synthetic peptides of the receptor. The four IgG mAbs characterized recognized epitopes localized to different regions on the TSH-R.E; amino acids 22-35 (A1O and A11, both IgG2b from H-2(b) animals), amino acids 402-415 (A7, IgG2b from H-2(b) animals) and amino acids 147-228 (A9, IgG1 from H-2(d) animals). Immunolocalization studies showed that mAb A9 recognized TSH-R.E on unfixed cryostat sections, where binding was localized to the basolateral plasma membrane of thyroid follicular cells, suggesting that this antibody reacts with the native receptor on thyroid cells. The binding of the mAbs A7, A10 and A11 was also restricted to the basal surface of thyroid cells, but only after acetone fixation of the sections, implying that the epitopes recognized on the amino and carboxyl terminus of the extracellular region of the receptor are not accessible on the native molecule. None of the mAbs stimulated cyclic AMP responses in COS-7 cells transiently transfected with full-length functioning TSH-R.E, whilst weak inhibition of binding of radiolabelled TSH to porcine membranes in a radioreceptor assay was apparent with mAb A10 and A11, but only at high concentrations of IgG. The ability of mAb A9 to bind to the native receptor without stimulating activity or inhibition of TSH binding suggests that antibody can bind to the central region of the TSH-R.E without perturbing receptor function. The availability of mAbs that recognize epitopes on different regions of the extracellular domain of TSH-R will lead to a better understanding of the autoantigenic regions on TSH-R implicated in disease activity.