Intraoperative 2D C-arm and 3D O-arm in children: a comparative phantom study

PURPOSE

Exposure to ionizing radiation is a concern for children during intraoperative imaging. We aimed to assess the radiation exposure to the paediatric patient with 2D and 3D imaging.

METHODS

To evaluate the radiation exposure, patient absorbed doses to the organs were measured in an anthropomorphic phantom representing a five-year-old child, using thermoluminescent dosimeters. For comparative purposes, organ doses were measured using a C-arm for one minute of fluoroscopy and one acquisition with an O-arm. The cone-beam was centred on the pelvis. Direct and scattered irradiations were measured and compared (Student's t-test). Skin entrance dose rates were also evaluated.

RESULTS

All radiation doses were expressed in µGy. Direct radiation doses of pelvic organs were between 631.22 and 1691.87 for the O-arm and between 214.08 and 737.51 for the C-arm, and were not significant (p = 0.07). Close scattered radiation on abdominal organs were between 25.11 and 114.85 for the O-arm and between 8.03 and 55.34 for the C-arm, and were not significant (p = 0.07). Far scattered radiation doses on thorax, neck and head varied from 0.86 to 6.42 for the O-arm and from 0.04 to 3.08 for the C-arm, and were significant (p = 0.02). The dose rate at the skin entrance was 328.58 µGy.s^-1 for the O-arm and 1.90 with the C-arm.

CONCLUSION

During imaging of the pelvis, absorbed doses for a 3D O-arm acquisition were higher than with one minute fluoroscopy with the C-arm. Further clinical studies comparing effective doses are needed to assess ionizing risks of the intraoperative imaging systems in children.

Genetic testing facilitates prepubertal diagnosis of congenital hypogonadotropic hypogonadism

Neonatal micropenis and cryptorchidism raise the suspicion of congenital hypogonadotropic hypogonadism (CHH), a rare genetic disorder caused by gonadotropin-releasing hormone deficiency. Low plasma testosterone levels and low gonadotropins during minipuberty provide a clinical diagnostic clue, yet these tests are seldomly performed in general practice. We report a male neonate with no family history of reproductive disorders who was born with micropenis and cryptorchidism. Hormonal testing at age 2.5 months showed low testosterone (0.3 nmol/L) and undetectable gonadotropins (luteinizing hormone and follicle-stimulating hormone both <0.5 U/L), suggestive of CHH. Genetic testing identified a de novo, heterozygous mutation in fibroblast growth factor receptor 1 (FGFR1 p.L630P). L630 resides on the ATP binding cleft of the FGFR1 tyrosine kinase domain, and L630P is predicted to cause a complete loss of receptor function. Cell-based assays confirmed that L630P abolishes FGF8 signaling activity. Identification of a loss-of-function de novo FGFR1 mutation in this patient confirms the diagnosis of CHH, allowing for a timely hormonal treatment to induce pubertal development. Therefore, genetic testing can complement clinical and hormonal assessment for a timely diagnosis of CHH in childhood.

[Inborn errors of metabolism: transition from childhood to adulthood]

Inborn errors of metabolism (IEM) are due to mutations of genes coding for enzymes of intermediary metabolism and are classified into 3 broad categories: 1) intoxication, 2) energy defect and 3) cellular organelles synthesis or catabolism defect. Improvements of therapy over these last 20 years has improved prognosis of children with IEM. These children grow up and should have their transition to specialized adult care. Adult patients with IEM are a relatively new phenomenon with currently only limited knowledge. Extrapolated pediatric guidelines are applied to the adult population taking into account adult life stages (social independence, pregnancy, aging process and potential long-term complications).

[How do Swiss family physicians treat subclinical hypothyroidism?]

Subclinical hypothyroidism is a common condition, and its prevalence increases with age. Currently, guidelines regarding the screening and treatment of subclinical hypothyroidism are controversial. An international survey of general practitioners (GPs), to which Swiss GPs also contributed, showed large inter-country variations in treatment strategies for subclinical hypothyroidism. These differences are mainly explained by the lack of strong evidence for the management of this condition. The European randomized-controlled clinical trial TRUST should help clarify recommendations for screening and thyroxin replacement for the elderly with subclinical hypothyroidism. Working in close collaboration with GPs in Switzerland for the recruitment of patients will ensure that the findings from this study will be applicable to primary care settings.

[Follow-up and management of children born small for gestational age a endocrine and metabolic aspects]

Children born premature and/or small for gestational age (SGA) are at risk of growth and metabolic abnormalities. Catch-up growth occurs usually before the age of 2. In the absence of sufficient catch up growth, growth hormone (GH) treatment should be evaluated under certain conditions. Children who were born premature and/or SGA are at higher risk of insulin resistance and metabolic abnormalities, especially in case of excessive weight gain during the first months of life. Puberty in these children occurs normally or slightly advanced, with no effect on gonadic function or fertility. Each step of the development of premature and/or SGA children present specific risks, which the pediatrician has to follow. If necessary, the pediatric endocrinologist will initiate a specific management.

[Caring for patients with pediatric endocrinopathies and diabetes into adulthood: challenges of an often difficult transition]

The success of therapies for a number of pediatric disorders has posed new challenges for the long-term follow-up of adolescents with chronic endocrinopathies. Unfortunately, too many patients are lost during the transfer from pediatric to adult clinics. The transition process should be well-organized and include the young person and family. Recognizing the special needs of these adolescents is an important step in developing patient-centered approaches to care that enable patients to develop autonomy and self care skills. Key elements in this process include structured policies and guidelines, communication and close collaboration between pediatric and adult clinics, and integrating nurse clinicians in the transition process to help close the gaps in care.

CHD7 mutations in patients initially diagnosed with Kallmann syndrome--the clinical overlap with CHARGE syndrome

Kallmann syndrome (KS) is the combination of hypogonadotropic hypogonadism and anosmia or hyposmia, two features that are also frequently present in CHARGE syndrome. CHARGE syndrome is caused by mutations in the CHD7 gene. We performed analysis of CHD7 in 36 patients with KS and 20 patients with normosmic idiopathic hypogonadotropic hypogonadism (nIHH) in whom mutations in KAL1, FGFR1, PROK2 and PROKR2 genes were excluded. Three of 56 KS/nIHH patients had de novo mutations in CHD7. In retrospect, these three CHD7-positive patients showed additional features that are seen in CHARGE syndrome. CHD7 mutations can be present in KS patients who have additional features that are part of the CHARGE syndrome phenotype. We did not find mutations in patients with isolated KS. These findings imply that patients diagnosed with hypogonadotropic hypogonadism and anosmia should be screened for clinical features consistent with CHARGE syndrome. If such features are present, particularly deafness, dysmorphic ears and/or hypoplasia or aplasia of the semicircular canals, CHD7 sequencing is recommended.

Importance of inhibin B in the regulation of FSH secretion in the human male

Regulation of FSH secretion in the male involves a complex balance between stimulation by GnRH from the hypothalamus, inhibitory feedback by sex steroids (T and E2) and inhibin B (Inh B) from the gonads, and autocrine/paracrine modulation by activin and follistatin within the pituitary. The aim of the present study was to delineate the feedback control of FSH in the human male with specific reference to the relative roles of sex steroids vs. Inh B. Two experimental human models were used: 1) normal (NL) men subjected to acute sex steroid withdrawal (-T, -E2, + Inh B), and 2) functional castrate males (-T, -E2, -Inh B). Nine NL men (age range, 25-45 yr) and three castrate males (age range, 23-47 yr) were studied. The NL men underwent acute sex steroid suppression using high dose ketoconazole (1-g loading dose, followed by 400 mg, orally, four times daily for 150 h). Gonadotropin secretion was characterized by frequent blood sampling every 10 min for 12 h at baseline and on d 3 and 6 of sex steroid ablation. In the three castrate subjects, blood sampling was performed every 5 min for 24 h 8 wk after discontinuing androgen replacement therapy. In the NL men, treatment with ketoconazole resulted in a decline to castrate levels in T (451 +/- 20 to 38 +/- 7 ng/dl; P < 0.0005) and E2 (39 +/- 4 to 15 +/- 2 pg/ml; P < 0.005) and a modest, but significant, decline in Inh B levels, which remained within the normal range (183 +/- 19 to 136 +/- 13 pg/ml; P < 0.005). This suppression of sex steroids was associated with a more marked increase in mean LH (9.5 +/- 0.9 to 24.9 +/- 2.0 IU/liter; P < 0.0001) than FSH levels (5.1 +/- 0.7 to 10.0 +/- 1.5 IU/liter; P < 0.005), with the latter not exceeding the normal adult male range. The castrate subjects had a mean T level of 66 +/- 8 ng/dl, an E2 level of 20 +/- 1 pg/ml, and undetectable Inh B levels. Despite a similar sex steroid milieu, the mean FSH levels observed in NL men after acute sex steroid ablation were approximately 6-fold lower than those seen in the castrate subjects (10.0 +/- 1.5 vs. 59.5 +/- 17.7 IU/liter; P < 0.0005). In contrast, mean LH levels in the NL men were less than 3-fold lower than those in castrate subjects (24.9 +/- 2.0 vs. 66.8 +/- 20.1 IU/liter; P < 0.005). From this human model of acute sex steroid withdrawal, we conclude that Inh B is likely to be the major feedback regulator of FSH secretion in the human male.

The fertile eunuch variant of idiopathic hypogonadotropic hypogonadism: spontaneous reversal associated with a homozygous mutation in the gonadotropin-releasing hormone receptor

Mutations in the GnRH receptor (GnRH-R) gene have been reported to cause idiopathic hypogonadotropic hypogonadism (IHH). Herein, we describe a 26-yr-old male with a mild phenotypic form of IHH, the fertile eunuch syndrome (IHH in the presence of normal testicular size and some degree of spermatogenesis), associated with a homozygous mutation (Gln106Arg) in the GnRH-R. This mutation, located in the first extracellular loop of the GnRH-R, has been previously shown to decrease but not eliminate GnRH binding. The proband had hypogonadal testosterone levels, detectable but apulsatile gonadotropin secretion, and a normal adult male testicular size of 17 mL at baseline. After only 4 months of treatment with hCG alone, he developed sperm in his ejaculate and his wife conceived. Following cessation of hCG therapy, the patient demonstrated reversal of his hypogonadotropism as evidenced by normal adult male testosterone levels and the appearance of pulsatile luteinizing hormone secretion. This case thus expands the emerging clinical spectrum of GnRH-R mutations, provides the first genetic basis for the fertile eunuch variant of IHH and documents the occurrence of reversible IHH in a patient with a GnRH-R mutation.

Prevalence, phenotypic spectrum, and modes of inheritance of gonadotropin-releasing hormone receptor mutations in idiopathic hypogonadotropic hypogonadism

Mutations in the GnRH receptor (GNRHR) have been described as a cause of reproductive failure in a subset of patients with idiopathic hypogonadotropic hypogonadism (IHH). Given the apparent rarity of these mutations, we set out to determine the frequency and distribution of GNRHR mutations in a heterogeneous population of patients with IHH who were well characterized with respect to diagnosis, phenotype, and mode of inheritance and to define their distribution within the receptor protein. One hundred and eight probands with IHH were screened for mutations in the coding sequence of GNRHR. Forty-eight of the 108 patients had a normal sense of smell, whereas the remaining 60 had anosmia or hyposmia (Kallmann syndrome). Exon segments in the GNRHR were screened for mutations using temperature gradient gel electrophoresis, and all mutations were confirmed by direct sequencing. Five unrelated probands (3 men and 2 women), all normosmic, were documented to have changes in the coding sequence of the GNRHR. Two of these probands were from a subgroup of 5 kindreds consistent with a recessive mode of inheritance, establishing a GNRHR mutation frequency of 2 of 5 (40%) in patients with normosmic, autosomal recessive IHH. The remaining 3 probands with GNRHR mutations were from a subgroup of 18 patients without evidence of familial involvement, indicating a prevalence of 3 of 18 (16.7%) in patients with sporadic IHH and a normal sense of smell. Among the five individuals bearing GNRHR mutations, a broad spectrum of phenotypes was noted, including testicular sizes in the male that varied from prepubertal to the normal adult male range. Three probands had compound heterozygous mutations, and two had homozygous mutations. Of the eight DNA sequence changes identified, four were novel: Thr(32)Ile, Cys(200)Tyr, Leu(266)Arg, and Cys(279)TYR: COS-7 cells transiently transfected with complementary DNAs encoding the human GNRHR containing each of these four novel mutations failed to respond to GnRH agonist stimulation. We conclude that 1) the spectrum of phenotypes in patients with GNRHR mutations is much broader than originally anticipated; 2) the frequency of GNRHR mutations may be more common than previously appreciated in familial cases of normosmic IHH and infrequent in sporadic cases; and 3) functional mutations of the GNRHR are distributed widely throughout the protein.

Characteristics of Caucasian type 2 diabetic patients during ketoacidosis and at follow-up

OBJECTIVE

To analyse among adult Caucasian patients hospitalised for diabetic ketoacidosis the relative frequency of patients with type 2 diabetes and their characteristics.

RESEARCH DESIGN

A retrospective review of adult patients presenting with diabetic ketoacidosis was conducted between 1993 and 1996. Patients with typical type 1 diabetes were classified according to age of onset < 35 years, insulin-dependence and BMI < 25 kg/m2; patients who did not meet these criteria were further classified on the basis of a basal and stimulated C-peptide and the detection of antibodies to glutamic acid decarboxylase (GADA) and to islet cells (ICA).

RESULTS

43 patients presenting with an episode of diabetic ketoacidosis were divided into two groups, A and B. Group A consisted of 19 patients, 17 patients classified as patients with typical type 1 diabetes and 2 patients with diabetes post-pancreatectomy. The other patients were the subjects of our study (group B; n = 20, 4 lost to follow-up). 13 patients (65% of group B = B I) were diagnosed with type 1 diabetes (median basal C-peptide: 0.15 nmol/l) and 7 patients (35% of group B = B II) with type 2 diabetes (median basal C-peptide of 1 nmol/l). Higher body mass index (BMI), shorter duration of diabetes, smaller anion gap and worse glycaemic control were found to be significantly different between groups B I and II on admission (p < 0.05). After a median follow-up of 18 months, patients in group B II had a better metabolic control than those in B I and 5 of the 7 patients were treated without insulin.

CONCLUSION

Diabetic ketoacidosis is more common than previously thought in patients with type 2 diabetes, occurring in 16% of all cases. Distinctive features at presentation are the degree of acidosis, the duration of diabetes, BMI and HbA1c. However, the basal plasma C-peptide value remains the best discriminating factor.