الفهرس 
THALASSEMIAOnly 14 pages are availabe for public view
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Abstract
T
hirty consecutive patients with secondary hemochromatosis due to transfusion-dependent thalassemia major (20 female, 10 male patients; age range, 12.40–25.50 years; mean age, 17.11±4.17 years underwent MR imaging examination of the pituitary gland. They were being treated with transfusion regimens and received iron chelation therapy with deferoxamine mesylate (Desferal; Ciba-Geigy, Basel, Switzerland),
Serum ferritin levels were measured in all patients by using radioimmunoassay to assess the severity of iron overload. Plasma luteinizing hormone, follicle-stimulating hormone and growth hormone levels were measured in all patients by using radioimmunoassay.
These laboratory data were collected to confirm the diagnosis of hypogonadism.
Fifteen (26.7%) of the 30 patients had a diagnosis of hypogonadism established with laboratory data and on clinical grounds, with impotence or poor sexual activity, testicular atrophy, and rarefaction of pubic hair. Thus, the patients were divided into two groups:
Group 1: Included, 8 thalassaemic patients with hypogonadism their chronological age ranged between 12.50 -16.00 years with a mean of 14.00±1.00 years. They were in Tanner 1, 2 stages.
Group 2: included, 22 thalassaemic patients without hypogonadism their chronological age ranged between 13.50 -25.50 years with a mean of 19.16±4.20 years. They were in Tanner 3, 4 and 5 stages.
Control Group: included 10 healthy children and adolescents, age and sex matched with the patients group and without any clinical conditions, their chronological age ranged between 9.0-18.0 years with mean of 12.40±2.85 years. They were 4 males and 6 females.
Radiological investigation:
MR images of the pituitary gland were acquired using a 1.5 T unit (Gyroscan® 515/ACS, Philips®). The MR protocol included a survey sagittal T1-weighted image (TR/TE, 654/18, slice thickness 8mm with intersection gap of 0.8 mm), and a sagittal T2*-weighted image on Fast Field Echo (FFE, Gradient) sequence (TR/TE, 650/30, flip angle 30., slice thickness 2mm with intersection gap of 0.2 mm). Signal intensities were measured in consensus by two investigators (A.C., A.H, the use of three operator-defined regions of interest (ROIs) of 3mm2 on sagittal T2*-weighted images and an average score was calculated (Christoforidis et al., 2007).
Image Analysis
The midline of the pituitary gland in the coronal plane was established, the mean signal intensity of the anterior lobe of the pituitary gland was determined as the mean of the signal intensities from three regions of interest placed in the midportion and the left and right sides of the anterior lobe.
All patients had elevated serum ferritin levels (mean3156.25 ± 740.38µg/L normal level, <300 µg/L), and their images showed reduction of signal intensity in the anterior lobe of the pituitary gland as compared with the signal intensity of the anterior lobe in control subjects (Specifically, the reduction in signal intensity was significantly different (P < .0001) between the 30(100%) patients and the control subjects, as well as between group 1 (8 [26.7%] of 30 patients) or group 2 (22 [73.3%] of 30 patients) and the control group
Therefore, the degree of signal intensity reduction in the anterior lobe of the pituitary gland was a reliable predictor in distinguishing group 1 patients from group 2 patients.
For all the patients, a negative correlation was found between the pituitary signal intensity and serum ferritin levels (r = -0.78, P < .001).
While the degree of signal intensity reduction was more pronounced in patients with higher serum ferritin levels, cases with hypogonadism showed significantly older chronological and bone age, lower mean height, sitting height, leg length, weight, span, higher mean ferritin, lower mean pituitary MRI SI, and lower LH level initially and after stimulation P<0.05
There was no statistical significant difference between Patients with intact pituitary function and those with hypogonadism as regards the mean HT SDS, wt /ht SDS, BMI, Hb%, GH and FSH initially and after stimulation P>0.05.
There was a negative moderate correlation between pituitary MRI SI and age (r= -0.48, r2=0.32, P=0.002).
Patients with hypogonadism showed significantly higher s ferritin compared to Patients with intact pituitary function P<0.05.
There was high significant difference between MRI signal intensity and Serum ferritin (r= -0.78, p <0.001).
There was a statistical significant increase in levels of GH, FSH and LH after stimulation compared to the baseline levels P<0.001.
Best cut off value was 369 with a sensitivity of 87.5%, specificity 68%, PPV 50% and NPV 94% with a diagnostic accuracy of 73%.
Cases with pituitary MRI SI < 369 were more than 15 likely to be involved in hypogonadism as those with level >369.
Excess iron deposition in the anterior lobe of the pituitary gland leads to secondary hypogonadism in advanced cases of transfusion-induced hemochromatosis.
We have shown that MR imaging with use of a GRE T2*-weighted pituitary signal intensity is a useful noninvasive tool for detecting adenohypophyseal iron overload in patients with transfusional hemochromatosis and for predicting the likelihood of pituitary dysfunction.