Evaluation of SDHB, SDHD and VHL gene susceptibility testing in the assessment of individuals with non-syndromic phaeochromocytoma, paraganglioma and head and neck paraganglioma.

OBJECTIVES: Research studies have reported that about a third of individuals with phaeochromocytoma/paraganglioma (PPGL) have an inherited predisposition, although the frequency of specific mutations can vary between populations. We evaluated VHL, SDHB and SDHD mutation testing in cohorts of patients with non-syndromic PPGL and head and neck paraganglioma (HNPGL). DESIGN: Prospective, observational evaluation of NHS practice. PATIENTS: Individuals with PPGL/HNPGL referred to a supraregional genetics testing service over a 10-year period. MEASUREMENTS: Clinical (age, tumour site, malignancy, etc.), mutation frequencies and characteristics. RESULTS: A total of 501 probands with PPGL (n = 413) or HNPGL (n = 88) were studied. Thirty-one percent of patients with PPGL presented had a pathogenic mutation in SDHB, SDHD or VHL. Mutation detection rates were highest in those with a positive family history (62%), malignancy (53%), multiple tumours (33%) or PGL (44%). Twenty-eight percent of individuals with a single sporadic phaeochromocytoma had a mutation. Overall, 63% of patients with HNPGL had a mutation (92% of those with a family history, 89% of those with multicentric tumours and 34% of those with a single sporadic HNPGL). Penetrance was calculated in 121 SDHB mutation-positive probands and 187 of their mutation-positive relatives. Most relatives were asymptomatic and lifetime penetrance in non-proband SDHB mutation carriers was <50%. CONCLUSIONS: Practice-based evaluations of genetic testing in PPGL reveal high mutation detection rates. Although clinical criteria can be used to prioritize mutation testing, mutations were detected in 'low risk groups' indicating a need for comprehensive and inexpensive genetic testing strategies for PPGL and HNPGL.

Tumor risks and genotype-phenotype-proteotype analysis in 358 patients with germline mutations in SDHB and SDHD.

Succinate dehydrogenase B (SDHB) and D (SDHD) subunit gene mutations predispose to adrenal and extraadrenal pheochromocytomas, head and neck paragangliomas (HNPGL), and other tumor types. We report tumor risks in 358 patients with SDHB (n=295) and SDHD (n=63) mutations. Risks of HNPGL and pheochromocytoma in SDHB mutation carriers were 29% and 52%, respectively, at age 60 years and 71% and 29%, respectively, in SDHD mutation carriers. Risks of malignant pheochromocytoma and renal tumors (14% at age 70 years) were higher in SDHB mutation carriers; 55 different mutations (including a novel recurrent exon 1 deletion) were identified. No clear genotype-phenotype correlations were detected for SDHB mutations. However, SDHD mutations predicted to result in loss of expression or a truncated or unstable protein were associated with a significantly increased risk of pheochromocytoma compared to missense mutations that were not predicted to impair protein stability (most such cases had the common p.Pro81Leu mutation). Analysis of the largest cohort of SDHB/D mutation carriers has enhanced estimates of penetrance and tumor risk and supports in silicon protein structure prediction analysis for functional assessment of mutations. The differing effect of the SDHD p.Pro81Leu on HNPGL and pheochromocytoma risks suggests differing mechanisms of tumorigenesis in SDH-associated HNPGL and pheochromocytoma.

Partial tachyphylaxis to somatostatin (SST) analogues in a patient with acromegaly: the role of SST receptor desensitisation and circulating antibodies to SST analogues.

OBJECTIVE: Somatostatin (SST) analogues are a key option in the management of a variety of conditions, including acromegaly. Tachyphylaxis to SST analogues is not documented in acromegaly. We describe such a phenomenon. DESIGN AND METHODS: A 74-year-old female with acromegaly previously treated with (90)Y implant, external radiotherapy and thrice daily s.c. octreotide had stable GH levels of 19 mU/l. GH progressively rose following switches to lanreotide and depot octreotide as Sandostatin LAR: from 29 to 126 mU/l. Magnetic resonance imaging and (111)In-pentetreotide scanning revealed no tumour growth or alteration in SST receptor (SSTR) status. Tachyphylaxis to SST analogues was considered. Therapy was discontinued and re-introduced in daily 200 microg/24 h increments by continuous s.c. infusion, to a maximum of 1000 microg/24 h, and maintained over 3 weeks with daily, followed by weekly, GH profiles. Competitive (125)I-octreotide radioligand binding assays measured in vitro bio-activity of anti-SST analogue antibodies. In vitro SSTR binding studies utilised SSTR-expressing rat cortex membrane. RESULTS: Median GH fell by 93% from 504 to 39.5 mU/l and rose reproducibly on continued infusion to 120 mU/l. Octreotide withdrawal for 16 h produced a 64% increase in sensitivity. High-affinity IgG anti-lanreotide (IC(50)=187 pmol/l) and anti-octreotide (IC(50)=82 nmol/l) antibody, with no crossreactivity with natural SST, was demonstrated. In vitro inhibition of (125)I-octreotide SSTR binding by anti-SST analogue crossreacting antibody was observed at 1:1 serum dilution. CONCLUSIONS: This is the first report of tachyphylaxis to SST analogues in acromegaly. We believe that the short time course of resensitisation following acute octreotide withdrawal is suggestive of an effect(s) on receptor function or on the receptor signal transduction cascade at sites further downstream, rather than an immune-mediated phenomenon.

Patient knowledge of antithyroid drug-induced agranulocytosis.

BACKGROUND: Agranulocytosis is a serious side effect of antithyroid drugs. OBJECTIVE: To ascertain the knowledge of patients and review the quality of information available on the internet. METHODS: A questionnaire survey was performed for patients receiving antithyroid drugs. Patients attending endocrine clinics who were receiving antithyroid drug treatment (group A, n = 33) were interviewed. A further national cohort of patients (group B, n = 100) treated with antithyroid drugs, participated in an online survey. RESULTS: 60.9% of responders were not aware of the common symptoms of agranulocytosis. 18.6% had never received any information about side effects. Of the 108 patients who recalled receiving information, 30% rated the quality as 'poor' or 'not good at all'. Structured interviews of group A patients revealed that almost half (45.5%, 15/33) had experienced symptoms that could be indicative of agranulocytosis, but only 53.3% (8/15) had a blood count checked. A review of 20 selected patient information internet sites revealed a significant variation in advice given to patients. CONCLUSIONS: Inadequate knowledge about agranulocytosis among patients receiving antithyroid drug treatment is common. The available information on the internet is variable and inconsistent.

Medical therapy of macroprolactinomas in males: I. Prevalence of hypopituitarism at diagnosis. II. Proportion of cases exhibiting recovery of pituitary function.

Hyperprolactinaemia frequently causes secondary hypogonadism through central suppression of gonadotropin secretion. Macroprolactinomas (> 1 cm diameter) are more common in males and may additionally cause more generalised hypopituitarism. Recovery of the thyrotropic and/or corticotropic axes is well described following selective adenomectomy, but remains poorly defined in relation to medical (dopamine-agonist) therapy of macroprolactinomas. We therefore performed a retrospective examination of case records of male patients who had received medical therapy alone for macroprolactinoma between 1980-2001 (n = 35) and in whom tumor shrinkage was documented by interval pituitary imaging (reported throughout by a single neuroradiologist). Mean prolactin level at baseline was 59,932 mU/L (median 31,400; range 3,215-332,000); mean period of follow up was 4.2 years (median 2.6; range: 1.0-15). Defects of the following axes were evident at diagnosis: LH/FSH-testosterone (n = 27; 77%), TSH-T4 (n = 14; 41%-not including one case with pre-existing 1 degress hypothyroidism), ACTH-cortisol (n = 8; 23%). Overall, 14 men (40%) were deficient in 1 axis, seven (20%) in 2 axes and seven (20%) in 3 axes. Growth hormone secretory status was not systematically evaluated. In all but 6 patients, prolactin levels fell to normal or near-normal levels (mean 764 mU/L; median 260; range: < 10-4,833). Of the patients in whom adequate reassessment had been performed, thyrotroph function recovered in 4/9, corticotroph function in 4/6 and gonadotroph function in 16/26 cases. In four cases (11%) previously described, development of visual impairment as a result of the chiasmal traction syndrome necessitated a dose reduction in medical therapy to allow a degree of controlled tumor re-expansion. The prevalence at diagnosis of TSH and ACTH deficiency in men with macroprolactinomas was 41% and 23%, respectively. Among eight patients with insufficiency of TSH and/or ACTH secretion who underwent complete interval reassessment over several years of treatment, recovery of at least one axis occurred in six cases (75%). This study highlights the importance of screening ACTH- and/or TSH-deficient men during dopamine agonist therapy in order to identify cases where hypopituitarism has resolved.

Pituitary apoplexy: a review of clinical presentation, management and outcome in 45 cases.

OBJECTIVE: To review clinical presentation, management and outcomes following different therapies in patients with pituitary apoplexy. METHODS: Retrospective analysis of case-records of patients with classical pituitary apoplexy treated in our hospitals between 1983-2004. RESULTS: Forty-five patients (28 men; mean age 49 years, range 16-72 years) were identified. Only 8 (18%) were known to have pituitary adenomas at presentation. Thirty-four (81%) patients had hypopituitarism at presentation. CT and MRI identified pituitary apoplexy in 28% and 91% cases, respectively. Twenty-seven (60%) patients underwent surgical decompression, whilst 18 (40%) were managed conservatively. Median time from presentation to surgery was 6 days (range 1-121 days). Patients with visual field defects were more likely than those without these signs to be managed surgically (p = 0.01). Complete or near-complete resolution occurred in 93% (13/14), 94% (15/16) and 93% (13/14) of the surgically treated patients with reduced visual acuity, visual field deficit and ocular palsy, respectively. All patients with reduced visual acuity (4/4), visual field deficit (4/4) and ocular palsy (8/8) in the conservative group had complete or near-complete recovery. Only 5 (19%) patients in the surgical group and 2 (11%) in the conservative group had normal pituitary function at follow up. One (4%) patient in the surgical group and 4 (22%) in the conservative group had a recurrence of pituitary adenoma. CONCLUSIONS: This large series suggests that the patients with classical pituitary apoplexy, who are without neuro-ophthalmic signs or exhibit mild and non-progressive signs, can be managed conservatively in the acute stage.