Subjects

The study included 30 patients with maxillofacial fractures (mean age, 38.14 ± 14.15 years, min–max, 18–65 years; 26 male, 4 female) and sex-matched 30 healthy controls (mean age, 42.77 ± 11.36 years, min–max, 20–63 years; 25 male, 5 female). In both groups, subjects within 18–65 years were included. In the control group, none had acute or chronic illnesses affecting the hypothalamic–pituitary axis including infection, malignancy, radiotherapy, endocrinological diseases or a history of drug use such as glucocorticoids. Patients included in the study were retrospectively screened. These patients had a history of maxillofacial fracture at least a year before (mean: 27.5 ± 6.5 months) and were monitored by the Erciyes University Medical School Plastic Surgery and Reconstruction Department. Patients did not have any chronic diseases, such as diabetes mellitus or chronic kidney disease, nor did they have a history of medication use, including corticosteroids. The following were the causes of head trauma; 13 patients had zygomatic fractures, 7 patients had Le fort 1–2, 6 patients had mandibular fractures, 3 patients had nasal fractures, and 1 patient had a blow-out fracture (Fig. 1). The level of consciousness of the patients was evaluated with Glasgow Coma Scale (GCS). A score of 13–15 indicates mild TBI, 9–12 indicates moderate TBI, and ≤ 8 indicates severe TBI. Patients with mild head trauma were included in the study group. All of the patients included in the study had GCS 15 during and after the trauma, according to hospital records and patient history. The ethics committee and the institutional review board of Erciyes University Medical School approved this study, and informed consent was obtained from each patient and control subject (Project number: TTU-2015-5747).

Fig. 1

Type of fracture in patients with maxillofacial trauma

Assessment of patient characteristics and biochemical parameters

Pituitary dysfunction was defined by basal hormone levels and/or hormonal response to dynamic tests. Internationally accepted criteria were used to diagnose pituitary hormone deficiencies, as detailed below. Both patients and controls were outpatients. Laboratory tests were performed after a thorough physical examination that included arterial blood pressure and heart rate. Lipid profile (total cholesterol, high-density lipoprotein cholesterol, triglycerides), fasting plasma glucose level, renal function tests (blood urea nitrogen, creatinine, uric acid, and electrolytes), liver function tests (alanine aminotransferase, aspartate aminotransferase, total alkaline phosphatase, total protein, albumin levels), and complete blood count were measured at the Department of Clinical Biochemistry, Erciyes University. Insulin resistance was assessed by calculating the homeostatic model assessment score (HOMA) using the formula: (fasting glucose [mg/dl] × fasting insulin [mU/l]/405).

Assessment of pituitary functionBasal hormone levels

Basal hormonal parameters were measured, including free T3, free T4, thyroid-stimulating hormone (TSH), prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), total testosterone in males, estradiol in women, GH and insulin-like growth factor 1 (IGF-I) levels.

In men, hypogonadotropic hypogonadism was defined as a total testosterone value of < 134 ng/dl in the presence of normal or low values of gonadotropins (reference range; FSH 0.95–11.95, LH 0.57–12.07). Hypogonadotropic hypogonadism was defined in premenopausal women as a serum estradiol level ≤ 11 pg/ml combined with an abnormally low or normal serum gonadotropin concentration (LH—follicular phase: 1.80–11.78 mIU/ml, ovulation phase: 7.79–89.08 mIU/ml, luteal phase: 0.56–14.00 mIU/ml; FSH—follicular phase: 3.03–8.8 mIU/ml, ovulation phase: 2.55–16.69 mIU/ml, luteal phase: 1.38–5.43 mIU/ml) [13, 14]. In women, menstrual history was obtained, and tests were performed on days 3–4 of the follicular phase. TSH deficiency was defined as a low serum-free T4 level (< 7.7 pg/ml) without an increase in serum TSH [13, 14].

Assessment of somatotropic and corticotropic function and definition of abnormalities

A low-dose ACTH stimulation test and glucagon stimulation test (GST) were used to assess the GH–IGF-I and ACTH–cortisol axis in patients and controls.

All patients and controls received a glucagon test (1 mg intramuscular glucagon; Novo Nordisk; with blood sampling for cortisol and GH at baseline, 90, 120, 150, 180, 210, and 240 min) to establish normal cortisol and GH response to glucagon stimulation, the cutoff value was estimated from the cortisol and GH responses of healthy controls. The GH response to glucagon was greater than 1.18 µg/l in all 30 healthy subjects (median 11.7 ± 11.45 μg/l; range 1.18–36.79 µg/l). Therefore, we took a cutoff of 1.18 µg/l as a normal GH response after glucagon administration [4, 11]. Cortisol levels in all 30 healthy subjects exceeded 9.1 µg/dl (median 21.17 ± 6.58 μg/dl; range 9.1–52.32 µg/dl). Therefore, we took 9.1 µg/l as a cutoff value of normal cortisol response [15]. Furthermore, a low-dose ACTH stimulation test with 1 µg tetracosactide intravenous (Synacthten, Novartis Pharma, Lion, France) was performed on all patients and controls, as previously described, and serum samples were obtained for cortisol measurement basally and at 30, 60, 90, and 120 min. ACTH deficiency was defined as a peak cortisol level of less than 12.5 µg/dl [15].

Analytic methods of hormonal parameters

The intra-assay and inter-assay coefficients of variation (CV) for serum GH were 1.5 and 14%, respectively. The minimum detection limit was 0.01 µg/l, and GH standards were calibrated according to the World Health Organization reference standard 88/624. The intra-assay and inter-assay for IGF-I were 3.4 and 8.2%, respectively, after formic acid–ethanol extraction (DSL). All the other serum hormones were measured using radioimmunoassay, IRMA, or chemiluminescent methods with the following commercial kits; cortisol (DSL; intra-assay and inter-assay CV: 8·4% and 9·1%), TSH-IRMA (Izotop; 7·3% and 3·8%), PRL (Advia Centaur System Chemiluminescent Technology, Bayer, Germany; 3·3% and 4·7%) sT3 (Izotop, Budapest, Hungary; 22% and 81%), sT4 (Izotop; 34% and 55%, FSH (Advia Centaur System Chemiluminescent Technology; 2·9% and 2·7%), LH (Advia Centaur System Chemiluminescent Technology; 2·3% and 1·5%), total testosterone (Biosource, Nivelles, Belgium; 4·6% and 6·2%), and estradiol ( 5·5% and 5·2%).

Statistical methods

Statistical analysis was performed using the SPSS 20.0 program. For normality, all data were subjected to the Kolmogorov–Smirnov test and Shapiro–Wilk test. Normally distributed values were presented as mean ± standard deviation (SD). Non-normally distributed values were presented as median (interquartile range). The ANOVA test was used to compare the differences between GH-deficient, GH-sufficient, and control groups for normally distributed values. The Kruskal–Wallis test and Mann–Whitney U test were used to compare the differences between subjects for the non-normally distributed values. The correlation between the variables was analyzed using Pearson’s correlation analysis. Linear regression analysis was used to determine the effect of independent variables on hormonal parameters. The significance level was determined as P value of < 0.05.