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Transient diabetes insipidus is a well-known complication after transsphenoidal surgery (TSS). On the other hand, transient hyponatremia has been reported as being a delayed complication of TSS. Transient hyponatremia has been attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), but the details of hyponatremia have not been clarified. In the present study, we retrospectively reviewed 110 consecutive patients (39 males and 71 females, age 9–80 years) operated on transsphenoidally for pituitary and hypothalamic tumors. We investigated the frequency, time of onset, duration of hyponatremia after TSS, and analyzed possible factors associated with it. A postoperative sodium concentration <135 mEq/l was observed in 29 (26%) patients. Five patients were excluded from this study because their hyponatremia could be due to either overdose of desmopressin or SIADH for meningitis. Therefore, we investigated 24 (22%) patients with hyponatremia in this study. The sodium levels in the patients with hyponatremia ranged from 110 to 134, with a mean of 126.2 ± 5.3 mEq/l. Hyponatremia was observed on average on postoperative day 9.5 ± 2.4, the serum sodium levels normalized within 3.8 ± 1.7 days. Hyponatremia occurred in patients with non-functioning pituitary adenoma (26%, 11/42), Rathke’s cleft cyst (29%, 5/17), prolactinoma (31%, 4/13) and acromegaly (15%, 4/27). 18 patients (75%, 6/24) who developed hyponatremia had macrotumor (>10 mm), and 6 patients (25%, 6/24) had microtumor. The plasma arginine vasopressin (AVP) levels in the patients with hyponatremia ranged from 0.21 to 2.1, with a mean of 0.79 ± 0.46 pg/ml, and the levels were inversely correlated with plasma osmolality (r = –0.80, p = 0.002). The urine to plasma osmolality ratios were >1. All the patients received appropriate hormonal replacement, including hydrocortisone. These data showed that postoperative hyponatremia after TSS was not rare, and the hyponatremia was mainly associated with SIADH. As the hyponatremia could be a life-threatening complication, all patients should be screened for serum electrolytes after TSS.

Growth hormone (GH) regulates somatic growth, substrate metabolism and body composition. Its actions are elaborated through the GH receptor (GHR). GHR signalling involves the role of at least three major pathways, STATs, MAPK, and PI3-kinase/Akt. GH receptor function can be modulated by changes to the ligand, to the receptor or by factors regulating signal transduction. Insights on the physico-chemical basis of the binding of GH to its receptor and the stoichiometry required for activation of the GH receptor-dimer has led to the development of novel GH agonists and antagonists. Owing to the fact that GH has short half-life, several approaches have been taken to create long-acting GHR agonists. This includes the pegylation, sustained release formulations, and ligand-receptor fusion proteins. Pegylation of a GH analogue (pegvisomant) which binds but not activate signal transduction forms the basis of a new successful approach to the treatment of acromegaly. GH receptors can be regulated at a number of levels, by modifying receptor expression, surface availability and signalling. Insulin, thyroid hormones and sex hormones are among hormones that modulate GHR through some of these mechanisms. Estrogens inhibit GH signalling by stimulating the expression of SOCS proteins which are negative regulators of cytokine receptor signalling. This review of GHR modulators will cover the effects of ligand modification, and of factors regulating receptor expression and signalling.

Objective The purpose of this study was to survey the clinical characteristics, complications, and therapeutic outcomein patients with acromegaly. Patients and Methods The clinical features of 65 patients with acromegaly (31 males, 34 females; mean age: 50±2 yr.) who were admitted to Tokyo Women's Medical University between 1990 and 1999 were analyzed retrospectively from medical records. Results The retrospective analysis revealed that the diagnosis of acromegaly was preceded by approximately 8.1±1.1 years of signs and symptoms of the disease. Fortysix of the 65 patients (71 %) had macroadenomas, 16 (25%) had microadenomas, and the remaining three had empty sella. The rate of biochemical cure or remission was 81 % for microadenoma (13/16), 64% for macroadenoma without extrasellar extension (9/14), and 13% for macroadenoma with cavernous sinus extension (2/15). Eighteen (28 % ) patients had impaired glucose tolerance (IGT) and 32 (49 %) had diabetes mellitus (DM). After treatment for acromegaly, glucose metabolism was analyzed again in 38 patients, and it improved in 26 patients with IGT or DM. Twenty-five of 65 patients (38%) had hypertension. Of 26 patients whounderwentbarium enemaor colonoscopy, 10 had colonic polyps and 4 had colon cancer. Conclusion This study suggests that long-term excessive growth hormone (GH) secretion causes many complications. Therefore, awareness of the early symptomsand signs of acromegaly and long-term careful managementof complications, along with therapy to reduce serum GH/insulin-like growth factor (IGF)-I levels, are important for patients with acromegaly. (Internal Medicine 40: 987-992, 2001)