Central diabetes insipidus (vasopressin deficiency) after surgery for pituitary tumours: A systematic review and meta-analysis.

OBJECTIVE: Central diabetes insipidus or vasopressin deficiency (AVP-D) is the most frequent water balance disorder after transsphenoidal surgery (TSS) with variable prevalence amongst studies. We aimed to determine rates of newly-developed transient or permanent AVP-D in patients with pituitary tumours treated with TSS. DESIGN AND METHODS: We performed systematic review of Medline, Embase and Cochrane Library between 01/01/2000-31/01/2021 for studies reporting on outcomes for pituitary adenoma, craniopharyngioma and Rathke's cleft cyst (RCC) after TSS and providing definition of post-operative AVP-D. We pooled the results as proportions with 95% confidence intervals (CIs) using Freeman-Tukey transformation random effects meta-analysis. RESULTS: From 11694 studies, 51 were included. Rates of transient or permanent AVP-D were: 17% (95% CI, 13-21) and 3% (95% CI, 2-5) in total group, 16% (95% CI, 12-21) and 2% (95% CI, 2-3) in pituitary adenomas, 31% (95% CI, 24-39) and 30% (95% CI, 22-39) in craniopharyngiomas, 35% (95% CI, 16-57) and 14% (95% CI, 6-23) in RCCs, respectively. Based on diagnostic criteria, rates of transient or permanent AVP-D were: for hypotonic polyuria, 14% (95% CI, 8-22) and 3% (95% CI, 1-4), for hypotonic polyuria and hypernatraemia, 21% (95% CI, 13-29) and 5% (95% CI, 2-11), for desmopressin administration, 22% (95% CI, 15-29) and 9% (95% CI, 0-30), respectively. CONCLUSIONS: Following TSS, a small proportion of patients with pituitary adenoma have permanent AVP-D (2%), but prevalence reaches 30% in ones with craniopharyngioma and 14% in those with RCC. Diagnostic criteria for post-operative AVP-D remain variable affecting reported rates of this condition.

Natural history of non-functioning pituitary microadenomas: results from the UK non-functioning pituitary adenoma consortium.

OBJECTIVE: The optimal approach to the surveillance of non-functioning pituitary microadenomas (micro-NFPAs) is not clearly established. Our aim was to generate evidence on the natural history of micro-NFPAs to support patient care. DESIGN: Multi-centre, retrospective, cohort study involving 23 endocrine departments (UK NFPA consortium). METHODS: Clinical, imaging, and hormonal data of micro-NFPA cases between January, 1, 2008 and December, 21, 2021 were analysed. RESULTS: Data for 459 patients were retrieved [median age at detection 44 years (IQR 31-57)-152 males/307 females]. Four hundred and nineteen patients had more than two magnetic resonance imagings (MRIs) [median imaging monitoring 3.5 years (IQR 1.71-6.1)]. One case developed apoplexy. Cumulative probability of micro-NFPA growth was 7.8% (95% CI, 4.9%-8.1%) and 14.5% (95% CI, 10.2%-18.8%) at 3 and 5 years, respectively, and of reduction 14.1% (95% CI, 10.4%-17.8%) and 21.3% (95% CI, 16.4%-26.2%) at 3 and 5 years, respectively. Median tumour enlargement was 2 mm (IQR 1-3) and 49% of micro-NFPAs that grew became macroadenomas (nearly all >5 mm at detection). Eight (1.9%) patients received surgery (only one had visual compromise with surgery required >3 years after micro-NFPA detection). Sex, age, and size at baseline were not predictors of enlargement/reduction. At the time of detection, 7.2%, 1.7%, and 1.5% patients had secondary hypogonadism, hypothyroidism, and hypoadrenalism, respectively. Two (0.6%) developed hypopituitarism during follow-up (after progression to macroadenoma). CONCLUSIONS: Probability of micro-NFPA growth is low, and the development of new hypopituitarism is rare. Delaying the first follow-up MRI to 3 years and avoiding hormonal re-evaluation in the absence of tumour growth or clinical manifestations is a safe approach for micro-NFPA surveillance.

UK practice on incidentally detected non-functioning pituitary microadenomas: analysis of two national surveys during a 12-year interval.

PURPOSE: The optimal management approach for presumed non-functioning pituitary microadenomas (microNFPAs) remains unclear. Our aim was to capture current UK practice and identify changes with time. METHODS: Two online surveys investigating clinicians' approaches were performed in 2009-2010 and 2021-2022 (advertised through Society for Endocrinology UK). RESULTS: 150 and 214 clinicians participated in the 2021 and 2009 survey, respectively (response rates 31.2% and 35.4%, respectively). At baseline, 2021 survey respondents were more likely to measure IGF-1 (96.0% vs 74.1%, p < 0.001) and morning cortisol (87.9% vs 62.6%, p < 0.001), and less likely GH (26.2% vs 42.6% p = 0.002), 24 h urine free cortisol (3.4% vs 23.2%, p < 0.0001) or dynamically assess adrenal reserve (11.4% vs 30.4%, p < 0.001). 47.2% of clinicians in 2021 would reassess pituitary function annually until discharge (in absence of tumour growth/symptoms). The 2021 survey respondents were more likely to stop imaging at or before 3 years (81.7% vs 44.3%, p < 0.001) and at or before 5 years (86.6.% vs 72.9%, p = 0.002), whilst 2009 survey respondents were more likely to continue imaging beyond 5 years (24% vs 7%, p < 0.001). Responses on imaging frequency/intervals showed notable variability in both surveys. CONCLUSIONS: Diagnostic and management approaches for microNFPAs have evolved in the UK. Biochemical investigations are performed in accord with consensus guidelines, though many clinicians perform annual biochemical surveillance without tumour growth/symptoms. A small number of clinicians request imaging beyond 5 years, but the frequency of imaging intervals until discharge remains variable. Robust evidence on the long-term natural history of microNFPAs is necessary to unify clinician approach.

Management of Nelson's Syndrome.

Nelson's syndrome is a potentially severe condition that may develop in patients with Cushing's disease treated with bilateral adrenalectomy. Its management can be challenging. Pituitary surgery followed or not by radiotherapy offers the most optimal tumour control, whilst pituitary irradiation alone needs to be considered in cases requiring intervention and are poor surgical candidates. Observation is an option for patients with small lesions, not causing mass effects to vital adjacent structures but close follow-up is required for a timely detection of corticotroph tumour progression and for further treatment if required. To date, no medical therapy has been consistently proven to be effective in Nelson's syndrome. Pharmacotherapy, however, should be considered when other management approaches have failed. A subset of patients with Nelson's syndrome may develop further tumour growth after primary treatment, and, in some cases, a truly aggressive tumour behaviour can be demonstrated. In the absence of evidence-based guidance, the management of these cases is individualized and tailored to previously offered treatments. Temozolomide has been used in patients with aggressive Nelson's with no consistent results. Development of tumour-targeted therapeutic agents are an unmet need for the management of aggressive cases of Nelson's syndrome.

Pre- and peri-operative characteristics, complications and outcomes of patients with biochemically silent pheochromocytomas; a case series.

PURPOSE: Pheochromocytomas are rare tumors and biochemically silent ones with normal catecholamine levels are even rarer. Up to date, biochemically inactive pheochromocytomas are poorly investigated. We aimed to systematically assess the pre- and peri-operative characteristics and the outcomes of patients with these tumors who had been treated and followed-up in 2 tertiary centers. METHODS: Clinical, laboratory and imaging data, treatment outcomes and follow-up of biochemically silent pheochromocytoma patients were recorded. RESULTS: Ten patients (5 men) [median age at diagnosis 52.5 years (24-72)] were included. Adrenal masses were incidentally discovered in all patients except from one who presented with pheochromocytoma-related manifestations. Twenty-four-hour urine metanephrine and normetanephrine levels were in the low-normal, normal and high-normal range in 4, 4 and 2 patients and in 1, 6 and 3 patients, respectively. Tumors were unilateral [median size 46 mm (17-125)] and high density on pre-contrast CT imaging or high signal intensity on T2-weighted MRI scans were found in all cases. Pre-operatively, 5 patients were treated with phenoxybenzamine [median total daily dose 70 mg (20-100)]. Intra-operatively, 4 patients developed hypertension requiring vasodilator administration and 8 developed hypotension; vasoconstrictors were required in 5 cases. One patient, not pre-operatively treated with phenoxybenzamine, developed Takotsubo cardiomyopathy. During a median 24-month (12-88) follow-up period, one patient had disease progression. CONCLUSIONS: The majority (90%) of patients with biochemically silent pheochromocytomas developed hemodynamic instability during adrenal surgery. In patients with biochemically silent adrenal lesions and a high suspicion index for pheochromocytoma based on tumor imaging characteristics, pre-operative alpha-blockade treatment may be advisable.

The diagnosis and management of Cushing's syndrome in pregnancy.

Endogenous Cushing's syndrome (CS) is rarely encountered during pregnancy. Clinical and biochemical changes in healthy pregnancy overlap with those seen in pregnancy complicated by CS; the diagnosis is therefore challenging and can be delayed. During normal gestation, adrenocorticotrophic hormone, corticotrophin-releasing hormone, cortisol, and urinary free cortisol levels rise. Dexamethasone administration fails to fully suppress cortisol in pregnant women without CS. Localisation may be hindered by non-suppressed adrenocorticotrophic hormone levels in a large proportion of those with adrenal CS; smaller corticotroph adenomas may go undetected as a result of a lack of contrast administration or the presence of pituitary hyperplasia; and inferior petrosal sinus sampling is not recommended given the risk of radiation and thrombosis. Yet, diagnosis is essential; active disease is associated with multiple insults to both maternal and foetal health, and those cured may normalise the risk of maternal-foetal complications. The published literature consists mostly of case reports or small case series affected by publication bias, heterogeneous definitions of maternal or foetal outcomes or lack of detail on severity of hypercortisolism. Consequently, conclusive recommendations, or a standardised management approach for all, cannot be made. Management is highly individualised: the decision for surgery, medical control of hypercortisolism or adoption of a conservative approach is dependent on the timing of diagnosis (respective to stage of gestation), the ability to localise the tumour, severity of CS, pre-existing maternal comorbidity, and, ultimately, patient choice. Close communication is a necessity with the patient placed at the centre of all decisions, with risks, benefits, and uncertainties around any investigation and management carefully discussed. Care should be delivered by an experienced, multidisciplinary team, with the resources and expertise available to manage such a rare and challenging condition during pregnancy.

Nelson's Syndrome: An Update.

Nelson's syndrome (NS) is a condition which may develop in patients with Cushing's disease after bilateral adrenalectomy. Although there is no formal consensus on what defines NS, corticotroph tumor growth and/or gradually increasing ACTH levels are important diagnostic elements. Pathogenesis is unclear and well-established predictive factors are lacking; high ACTH during the first year after bilateral adrenalectomy is the most consistently reported predictive parameter. Management is individualized and includes surgery, with or without radiotherapy, radiotherapy alone, and observation; medical treatments have shown inconsistent results. A subset of tumors demonstrates aggressive behavior with challenging management, malignant transformation and poor prognosis.

Outcomes of Patients with Nelson's Syndrome after Primary Treatment: A Multicenter Study from 13 UK Pituitary Centers.

CONTEXT: Long-term outcomes of patients with Nelson's syndrome (NS) have been poorly explored, especially in the modern era. OBJECTIVE: To elucidate tumor control rates, effectiveness of various treatments, and markers of prognostic relevance in patients with NS. PATIENTS, DESIGN, AND SETTING: Retrospective cohort study of 68 patients from 13 UK pituitary centers with median imaging follow-up of 13 years (range 1-45) since NS diagnosis. RESULTS: Management of Cushing's disease (CD) prior to NS diagnosis included surgery+adrenalectomy (n = 30; eight patients had 2 and one had 3 pituitary operations), surgery+radiotherapy+adrenalectomy (n = 17; two received >1 courses of irradiation, two had ≥2 pituitary surgeries), radiotherapy+adrenalectomy (n = 2), and adrenalectomy (n = 19). Primary management of NS mainly included surgery, radiotherapy, surgery+radiotherapy, and observation; 10-year tumor progression-free survival was 62% (surgery 80%, radiotherapy 52%, surgery+radiotherapy 81%, observation 51%). Sex, age at CD or NS diagnosis, size of adenoma (micro-/macroadenoma) at CD diagnosis, presence of pituitary tumor on imaging prior adrenalectomy, and mode of NS primary management were not predictors of tumor progression. Mode of management of CD before NS diagnosis was a significant factor predicting progression, with the group treated by surgery+radiotherapy+adrenalectomy for their CD showing the highest risk (hazard ratio 4.6; 95% confidence interval, 1.6-13.5). During follow-up, 3% of patients had malignant transformation with spinal metastases and 4% died of aggressively enlarging tumor. CONCLUSIONS: At 10 years follow-up, 38% of the patients diagnosed with NS showed progression of their corticotroph tumor. Complexity of treatments for the CD prior to NS diagnosis, possibly reflecting corticotroph adenoma aggressiveness, predicts long-term tumor prognosis.

Recurrence in silent corticotroph adenomas after primary treatment: A systematic review and meta-analysis.

CONTEXT: 2017 WHO Classification of Pituitary Tumors grades silent corticotroph adenomas (SCAs) as "high-risk adenomas" due to their aggressive clinical behavior (high probability of recurrence). However, studies comparing recurrence rates of SCAs with other non-functioning pituitary adenoma (NFPAs) subtypes have provided conflicting results. OBJECTIVE: Estimate recurrence rates of SCAs after primary treatment (surgery±radiotherapy) and recurrence rate ratios (RRR) between SCAs and other NFPA subtypes. METHODS: Systematic review of published literature reporting on outcomes of SCAs up to October 31, 2017 was conducted. Recurrence rates, RRRs, 95% confidence intervals (CIs) were estimated from each study and pooled using random effects meta-analysis model. RESULTS: For determination of SCAs recurrence rates, 14 studies (low risk of bias, 297 patients) were selected; recurrence rate was 5.96 (95% CI, 4.3-7.84) per 100 person-years. Based on studies with mean follow-up <5 or ≥5 years, 25% (cumulative incidence 0.25; 95% CI, 0.13-0.38) and 31% (cumulative incidence 0.31; 95% CI, 0.23-0.40) of SCAs had recurrence, respectively. Recurrence rates after surgery or surgery+radiotherapy were 5.41 (95% CI, 3.28-7.96) and 4.88 (95% CI, 0.67-11.54) cases per 100 person-years, respectively. Analysis of 10 eligible studies (moderate risk of bias, 244 SCAs, 1622 NFPAs) showed no significant RRR (1.44; 95% CI, 0.9-2.33, p=0.130) between the groups. Focus on tumors treated solely by surgery also revealed no significant RRR (1.17; 95% CI, 0.79-1.75, p=0.429). CONCLUSIONS: Based on studies with mean follow-up ≥5 years, 31% of SCAs have recurrence. No evidence supporting higher recurrence risk of SCAs compared with other NFPA subtypes was found.

Impact of menopause on outcomes in prolactinomas after dopamine agonist treatment withdrawal.

OBJECTIVE: Discontinuation of dopamine agonist (DA) treatment in women with prolactinoma after menopause is a potential approach; studies systematically assessing long-term outcomes are lacking. Our aim was to investigate the natural history of prolactinoma in this group. DESIGN/PATIENTS: Retrospective cohort study of women with prolactinoma diagnosed before menopause and who after menopause were not on DA. RESULTS: Thirty women were included. Twenty-eight received DA (median duration 18 years, median age at DA withdrawal 52 years). At last assessment (median follow-up 3 years) and compared with values 6-12 months after stopping DA, Prolactin (PRL) increased in 15%, decreased but not normalized in 33% and was normal in 52%; PRL levels or visible adenoma on imaging before DA withdrawal, treatment duration and presence of macro-/microadenoma at diagnosis were not predictors of normoprolactinaemia at last review, whereas PRL values 6-12 months after stopping DA were. Adenoma regrowth was detected in 2/27 patients (7%), who showed gradual increase in PRL. Comparison with 28 women who had DA withdrawal before their menopause revealed lower risk of hyperprolactinaemia recurrence in the postmenopausal group (HR:0.316, 95% CI: 0.101-0.985, P < .05). Two women with microprolactinoma diagnosed in perimenopausal period had not been offered DA; PRL decreased (but not normalized) during observation of 1 and 8 years. CONCLUSIONS: Prolactin normalized over time in nearly half of the women and serum PRL 6-12 months after DA withdrawal is useful predictor. Nonetheless, 7% of the patients demonstrated adenoma regrowth which, given the life expectancy postmenopause, necessitate regular monitoring of the cases with persistent hyperprolactinaemia.

A rare challenging case of co-existent craniopharyngioma, acromegaly and squamous cell lung cancer.

Co-existence of craniopharyngioma and acromegaly has been very rarely reported. A 65-year-old man presented with visual deterioration, fatigue and frontal headaches. Magnetic resonance imaging revealed a suprasellar heterogeneous, mainly cystic, 1.9 × 2 × 1.9 cm mass compressing the optic chiasm and expanding to the third ventricle; the findings were consistent with a craniopharyngioma. Pituitary hormone profile showed hypogonadotropic hypogonadism, mildly elevated prolactin, increased insulin-like growth factor 1 (IGF-1) and normal thyroid function and cortisol reserve. The patient had transsphenoidal surgery and pathology of the specimen was diagnostic of adamantinomatous craniopharyngioma. Post-operatively, he had diabetes insipidus, hypogonadotropic hypogonadism and adrenocorticotropic hormone and thyroid-stimulating hormone deficiency. Despite the hypopituitarism, his IGF-1 levels remained elevated and subsequent oral glucose tolerance test did not show complete growth hormone (GH) suppression. Further review of the pre-operative imaging revealed a 12 × 4 mm pituitary adenoma close to the right carotid artery and no signs of pituitary hyperplasia. At that time, he was also diagnosed with squamous cell carcinoma of the left upper lung lobe finally managed with radical radiotherapy. Treatment with long-acting somatostatin analogue was initiated leading to biochemical control of the acromegaly. Latest imaging has shown no evidence of craniopharyngioma regrowth and stable adenoma. This is a unique case report of co-existence of craniopharyngioma, acromegaly and squamous lung cell carcinoma that highlights diagnostic and management challenges. Potential effects of the GH hypersecretion on the co-existent tumours of this patient are also briefly discussed. LEARNING POINTS: Although an extremely rare clinical scenario, craniopharyngioma and acromegaly can co-exist; aetiopathogenic link between these two conditions is unlikely.Meticulous review of unexpected biochemical findings is vital for correct diagnosis of dual pituitary pathology.The potential adverse impact of GH excess due to acromegaly in a patient with craniopharyngioma (and other neoplasm) mandates adequate biochemical control of the GH hypersecretion.

Mortality in patients with non-functioning pituitary adenoma.

Non-functioning pituitary adenomas (NFA) are benign pituitary neoplasms not associated with clinical evidence of hormonal hypersecretion. A substantial number of patients with NFA have morbidities related to the tumor and possible recurrence(s), as well as to the treatments offered. Studies assessing the long-term mortality of patients with NFA are limited. Based on the published literature of the last two decades, overall, the standardized mortality ratios in this group suggest mortality higher than that of the general population with deaths attributed mainly to circulatory, respiratory and infectious causes. Women seem to have higher mortality ratios, and assessment of time trends suggests improvement over the years. There is no consensus on predictive factors of mortality but those most consistently identified are older age at diagnosis and high doses of glucocorticoid substitution therapy. Well designed and of adequate power studies are needed to establish the significance of factors compromising the survival of patients with NFA and to facilitate improvements in long-term prognosis.

Familial partial lipodystrophy and proteinuric renal disease due to a missense c.1045C > T LMNA mutation.

Proteinuric renal disease is prevalent in congenital or acquired forms of generalized lipodystrophy. In contrast, an association between familial partial lipodystrophy (FPLD) and renal disease has been documented in very few cases. A 22-year-old female patient presented with impaired glucose tolerance, hyperinsulinemia, hirsutism and oligomenorrhea. On examination, there was partial loss of subcutaneous adipose tissue in the face, upper and lower limbs, bird-like facies with micrognathia and low set ears and mild acanthosis nigricans. Laboratory investigations revealed hyperandrogenism, hyperlipidemia, elevated serum creatine kinase and mild proteinuria. A clinical diagnosis of FPLD of the non-Dunnigan variety was made; genetic testing revealed a heterozygous c.1045C > T mutation in exon 6 of the LMNA gene, predicted to result in an abnormal LMNA protein (p.R349W). Electromyography and muscle biopsy were suggestive of non-specific myopathy. Treatment with metformin and later with pioglitazone was initiated. Due to worsening proteinuria, a renal biopsy was performed; histological findings were consistent with mild focal glomerular mesangioproliferative changes, and the patient was started on angiotensin-converting enzyme inhibitor therapy. This is the fourth report of FPLD associated with the c.1045C > T missense LMNA mutation and the second with co-existent proteinuric renal disease. Patients carrying this specific mutation may exhibit a phenotype that includes partial lipodystrophy, proteinuric nephropathy, cardiomyopathy and atypical myopathy. LEARNING POINTS: Lipodystrophy is a rare disorder characterized by the complete or partial loss of subcutaneous adipose tissue, insulin resistance, diabetes mellitus and hyperlipidemia.Proteinuric renal disease is a prevalent feature of generalized lipodystrophy but rare in familial partial lipodystrophy.Patients carrying the c.1045C > T missense LMNA mutation (p.R349W) may present with familial partial lipodystrophy, proteinuric nephropathy, cardiomyopathy and atypical myopathy.

Tyrosine Kinase Inhibitors and Diabetes: A Novel Treatment Paradigm?

Deregulation of protein tyrosine kinase (PTK) activity is implicated in various proliferative conditions. Multi-target tyrosine kinase inhibitors (TKIs) are increasingly used for the treatment of different malignancies. Recently, several clinical cases of the reversal of both type 1 and 2 diabetes mellitus (T1DM, T2DM) during TKI administration have been reported. Experimental in vivo and in vitro studies have elucidated some of the mechanisms behind this effect. For example, inhibition of Abelson tyrosine kinase (c-Abl) results in ß cell survival and enhanced insulin secretion, while platelet-derived growth factor receptor (PDGFR) and epidermal growth factor receptor (EGFR) inhibition leads to improvement in insulin sensitivity. In addition, inhibition of vascular endothelial growth factor receptor 2 (VEGFR2) reduces the degree of islet cell inflammation (insulitis). Therefore, targeting several PTKs may provide a novel approach for correcting the pathophysiologic disturbances of diabetes.

Cushing's Syndrome Due to CRH and ACTH Co-secreting Pancreatic Tumor--Presentation of a New Case Focusing on Diagnostic Pitfalls.

Cushing's syndrome (CS) due to a corticotropin-releasing hormone (CRH) and adrenocorticotropin hormone (ACTH) co-secreting tumor is very rare, and diagnosis can be difficult. We describe a case of CS caused by ectopic CRH and ACTH production from a pancreatic neuroendocrine tumor (pNET) and discuss possible pitfalls in the diagnosis. A 48-year-old woman presented with gradual increase in body weight, muscle weakness, and difficult to control hypertension. Laboratory and imaging investigations revealed ACTH-dependent hypercortisolemia and a 3-cm mass at the head of the pancreas. The patient underwent partial pancreatoduodenectomy. Histological examination revealed a well-differentiated pNET, expressing both CRH and ACTH. After a follow-up period of 18 months, she remains asymptomatic with no metastatic disease. This is the fourth case report of CS in adults due to an ectopic ACTH- and CRH-secreting pNET. Co-secretion of ACTH and CRH by the same tumor may cause diagnostic problems since investigation depends on which of the two hormones is secreted in greater amounts. Measurement of plasma CRH may help in establishing the diagnosis, especially in patients in whom endocrine tests are indicative of ectopic CS, whereas imaging findings are suggestive of pituitary hyperplasia.

The emerging role of denosumab in the long-term management of parathyroid carcinoma-related refractory hypercalcemia.

OBJECTIVE: The main cause of death in patients with parathyroid carcinoma is parathyroid hormone (PTH)-induced hypercalcemia. To date, the management of hypercalcemia has been based on the use of bisphosphonates and calcimimetic agents. In recent reports, the use of denosumab has shown encouraging results in cases of refractory hypercalcemia of malignancy. Our objective is to present a case of successful management of resistant hypercalcemia due to parathyroid carcinoma with denosumab, to review similar cases from the literature, and to propose denosumab's use in the clinical management of PTH-induced refractory hypercalcemia. METHODS: Presentation of a case report and review of the literature for cases of parathyroid carcinoma-mediated hypercalcemia successfully treated with denosumab. RESULTS: A 71-year-old man with metastatic parathyroid carcinoma was referred to our department for uncontrolled hypercalcemia, resistant to treatment with bisphosphonates and cinacalcet. Treatment with denosumab (120 mg per month) in addition to cinacalcet (180 mg per day) resulted in normalization of calcium levels and maintenance within the normal range for an observation period of 11 months. Review of the literature revealed 4 case reports and a letter to the editor, all of which reported the successful treatment of resistant hypercalcemia associated with parathyroid carcinoma. CONCLUSION: Based on the above findings of the effectiveness of denosumab in controlling refractory hypercalcemia, its safety in renal failure and the fact that denosumab may reduce PTH-induced bone loss, we endorse its use in the management of hypercalcemia in patients with parathyroid carcinoma and perhaps other conditions with PTH-induced hypercalcemia.

Severe resistant hypoglycemia in a patient with a pancreatic neuroendocrine tumor on sunitinib treatment.

OBJECTIVE: Sunitinib is a tyrosine kinase inhibitor used in the therapy of pancreatic neuroendocrine tumors (PNETs), metastatic renal cancer and gastrointestinal stromal tumors. We describe a patient with PNET who presented with severe hypoglycemia following sunitinib administration. CASE REPORT: A 64-year old man with known metastatic PNET presented with a history of recurring episodes of severe, life-threatening hypoglycemia 3 months after initiation of sunitinib treatment. Investigations during symptomatic hypoglycemia revealed inappropriately increased plasma insulin and C-peptide levels, consistent with endogenous hyperinsulinemia. No immune staining for insulin was observed in tissue samples from peritoneal metastatic tumor lesions, and serum anti-insulin antibodies were negative. Medical management with diazoxide, methylprednisolone and ocreotide was ineffective; continuous intravenous infusion of glucagon was required to maintain euglycemia. Following discontinuation of sunitinib there was gradual improvement in both the severity and frequency of the hypoglycemia. Six months later, the patient remained free of hypoglycemic episodes. CONCLUSIONS: We describe a patient with PNET who experienced severe, life-threatening hypoglycemia following sunitinib use. It is important that glucose levels of patients treated with sunitinib are monitored on a regular basis; those patients with diabetes may need to have their antidiabetic treatment adjusted to prevent hypoglycemia.