Efficacy, safety and population pharmacokinetics of sapropterin in PKU patients <4 years: results from the SPARK open-label, multicentre, randomized phase IIIb trial.

BACKGROUND: Sapropterin dihydrochloride, a synthetic formulation of BH4, the cofactor for phenylalanine hydroxylase (PAH, EC 1.14.16.1), was initially approved in Europe only for patients ≥4 years with BH4-responsive phenylketonuria. The aim of the SPARK (Safety Paediatric efficAcy phaRmacokinetic with Kuvan®) trial was to assess the efficacy (improvement in daily phenylalanine tolerance, neuromotor development and growth parameters), safety and pharmacokinetics of sapropterin dihydrochloride in children <4 years. RESULTS: In total, 109 male or female children <4 years with confirmed BH4-responsive phenylketonuria or mild hyperphenylalaninemia and good adherence to dietary treatment were screened. 56 patients were randomly assigned (1:1) to 10 mg/kg/day oral sapropterin plus a phenylalanine-restricted diet or to only a phenylalanine-restricted diet for 26 weeks (27 to the sapropterin and diet group and 29 to the diet-only group; intention-to-treat population). Of these, 52 patients with ≥1 pharmacokinetic sample were included in the pharmacokinetic analysis, and 54 patients were included in the safety analysis. At week 26 in the sapropterin plus diet group, mean phenylalanine tolerance was 30.5 (95% confidence interval 18.7-42.3) mg/kg/day higher than in the diet-only group (p < 0.001). The safety profile of sapropterin, measured monthly, was acceptable and consistent with that seen in studies of older children. Using non-linear mixed effect modelling, a one-compartment model with flip-flop pharmacokinetic behaviour, in which the effect of weight was substantial, best described the pharmacokinetic profile. Patients in both groups had normal neuromotor development and stable growth parameters. CONCLUSIONS: The addition of sapropterin to a phenylalanine-restricted diet was well tolerated and led to a significant improvement in phenylalanine tolerance in children <4 years with BH4-responsive phenylketonuria or mild hyperphenylalaninemia. The pharmacokinetic model favours once per day dosing with adjustment for weight. Based on the SPARK trial results, sapropterin has received EU approval to treat patients <4 years with BH4-responsive phenylketonuria. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01376908 . Registered June 17, 2011.

Rare diseases research and practice.

Rare diseases (RDs) affect less than 5 per 10,000 individuals in Europe, while in the USA a rare condition is considered to have a prevalence of fewer than 200,000 affected Americans. RDs stem as one of the most urgent and emerging health problems worldwide, creating a substantial personal, community and financial burden globally. However, available data are only declared on the basis of hearsay evidence, in the absence of strong methodological supports. Creation and implementation of international and national registries could allow the achievement of more reliable data. Disorders of sex development (DSD) are rare and heterogeneous conditions that can be isolated diseases or be part of more complex disorders. Their phenotypic appearance and timing of presentation are quite variable. A wide array of genes has been found to cause DSD, and recent years have witnessed many advances in the diagnosis of patients with DSD with the introduction of chromosomal microarrays and increased availability of gene sequencing. The focus on care and treatment has shifted from early gender assignment and corrective surgery to careful and appropriate diagnosis, proper education of patients and their families, psychological support and individualised treatment driven by a multidisciplinary team. This chapter aims to contribute to the understanding of the fundamental processes of healthcare organisation, research, on-going treatments, prevention and public health policies that regulate and are underlying RDs, including DSD.

Comparison between liquid and tablet formulations of levothyroxine in the initial treatment of congenital hypothyroidism.

OBJECTIVE: To evaluate the effects of liquid (drops) and tablet formulations of levothyroxine in homogeneous groups of infants with congenital hypothyroidism (CH) as diagnosed through neonatal screening. STUDY DESIGN: Forty-two consecutive infants with CH were subdivided into 2 groups consisting of infants with the severe or the moderate/mild form. For each form, the infants with CH were randomly assigned to receive liquid (group 1) or tablet (group 2) formulation. In all patients, thyroid function tests were performed before the beginning of therapy and at 15 and 30 days and at 3 and 6 months after the beginning of therapy. RESULTS: In the severe form, after 15 days of treatment, serum thyrotropin (TSH) levels became normal in 8 of 9 patients in group 1 and in 5 of 9 patients in group 2; serum free triiodothyronine (fT3) levels were significantly higher in group 1 than in group 2; and serum fT4 levels were higher than the upper limit of the normal range in all patients in both groups. During the follow-up, there were significantly more patients with suppressed TSH concentrations in group 1 than in group 2. In the moderate/mild form, the patients of group 1 and group 2 showed median values of TSH, fT3, and fT4 that were not significantly different. No clinical or electrocardiographic signs of heart disease were found. There were no significant differences in the developmental quotient between group 1 and group 2 patients with severe and moderate/mild CH. CONCLUSIONS: Our data seem to indicate that there is not complete bioequivalence between drops and tablets, especially in infants with severe CH.

Current loss-of-function mutations in the thyrotropin receptor gene: when to investigate, clinical effects, and treatment.

Thyroid-stimulating hormone receptor (TSHR) loss-of-function (LOF) mutations lead to a wide spectrum of phenotypes, ranging from severe congenital hypothyroidism (CH) to mild euthyroid hyperthyrotropinemia. The degree of TSH resistance depends on the severity of the impairment of the receptor function caused by the mutation and on the number of mutated alleles In this review data about genotype-phenotype correlation and criteria for clinical work-up will be presented and discussed. Complete TSH resistance due to biallelic LOF TSHR mutations must be suspected in all patients with severe not syndromic CH and severe thyroid hypoplasia diagnosed at birth by neonatal screening. Partial forms of TSH resistance show a more heterogeneous hormonal and clinical pattern . In these cases TSH serum levels are above the upper limit of normal range for the age but with a very variable pattern, free thyroxine (T4) concentrations are within the normal range and thyroid size can be normal or hypoplastic at ultrasound scan. An early substitutive treatment with L-T4 must be mandatory in all patients with severe CH due to complete uncompensated TSH resistance diagnosed at birth by neonatal screening. The usefulness of substitutive treatment appears much more controversial inpatients with subclinical hypothyroidism due to partial TSH resistance in whom the increased TSH concentration should be able to compensate the mild functional impairment of the mutant receptor. Together with standard criteria we recommend also an accurate clinical work-up to select patients who are candidates for a LOF TSHR mutation.

Levothyroxine treatment in pediatric benign thyroid nodules.

AIM: To evaluate the effectiveness of levothyroxine therapy in benign thyroid nodules in pediatrics. METHODS: Data from 78 euthyroid children and adolescents with benign thyroid nodules were retrospectively collected. Subjects were divided into 2 groups: levothyroxine treated (n = 36) and nontreated (n = 42), and the clinical, laboratory and sonographic features of the 2 groups were compared. Nodules were considered benign according to histology, fine-needle aspiration biopsy or by features suggestive for benignity. The groups were followed up for 2.4 ± 1.3 years, and treated patients received a mean dose of levothyroxine of 1.69 ± 0.66 µg/kg/day. RESULTS: Patients in the treated and nontreated groups were comparable for age, sex and follow-up. A reduction in nodule diameter from 2.24 ± 0.94 to 1.86 ± 1.17 cm (p = 0.039) was observed in treated patients, whereas the nodule diameter increased from 1.66 ± 0.86 to 1.78 ± 0.91 cm in nontreated patients (p = 0.024). In the treatment group, 11 patients (30.6%) had a reduction greater than 50% and significantly decreased palpable nodules (p < 0.001). A nonsignificant reduction in reported symptoms was observed, too. The change in nodule size was directly correlated with thyroid-stimulating hormone levels (r = 0.640, p < 0.001) and inversely with levothyroxine dose (r = -0.389, p = 0.009). In nontreated subjects, both palpable nodules and symptoms increased. CONCLUSION: This study supports levothyroxine treatment effectiveness in shrinking benign nodules.

Psychological and behavioural aspects in children and adolescents with congenital hypothyroidism diagnosed by neonatal screening: comparison between parents' and children's perceptions.

OBJECTIVE: To compare the psychological adjustment and behaviour of congenital hypothyroidism (CH) children and their parents with a control group. STUDY DESIGN: A cross-sectional study was carried out with 84 CH subjects diagnosed by neonatal screening (range 2.7-18.6 years), subdivided into four age groups: group 1 (2-5 years); group 2 (6-10 years); group 3 (11-13 years); and group 4 (14-18 years) and was compared with an age-matched control group. Patients were assessed using two questionnaires: Child Behaviour Checklist for parents and Youth Self-Report for children over 11 years of age. RESULTS: In groups 1, 3 and 4, total score (TS), internalising score (IS=problems within the self) and externalising score (ES=conflicts with other people) as reported by parents were not significantly different in CH patients and in controls. In group 2, parents of CH children showed values of TS (P<0.05), IS (P<0.05), ES (P<0.05) and scores on other scales significantly higher than controls. In self-reports of groups 3 and 4, the behavioural scales were not significantly different in CH patients and in controls. CONCLUSIONS: Paediatricians should be informed about the increased risk of the development of behavioural problems at primary school age in CH patients. At this age special attention should be paid to parental worries and anxiety. However, it can be reassuring for the patients and parents to know that the problems may be related to CH, and that they may spontaneously disappear.

Long-term clinical significance of thyroid autoimmunity in children with celiac disease.

OBJECTIVE: To evaluate the long-term outcome of thyroid function and autoimmunity in a large series of children with celiac disease. STUDY DESIGN: This longitudinal, retrospective study (duration of follow-up, 8.9 +/- 4.0 years) was conducted at the Pediatric Department, University of Bologna, Italy. One hundred thirty-five consecutive patients diagnosed between June 1990 and December 2004 and followed on a gluten-free diet were examined. Inclusion criteria were good dietary compliance and duration of follow-up for at least 3 years. RESULTS: Of 101 patients who never showed positive antithyroid titers during the follow-up, 86 remained euthyroid; 15 showed high thyroid-stimulating hormone values at diagnosis that normalized in 11 cases after 12 to 18 months of gluten withdrawal. Of 31 patients with persistently positive antibody titers, 23 (74%) remained consistently euthyroid during the follow-up and 8 (26%) had a subclinical hypothyroidism. The prevalence of cases with positive antibodies was similar in children with growth retardation or gastroenterological symptoms at diagnosis and different durations of gluten exposure. CONCLUSIONS: The presence of antithyroid antibodies in children with celiac disease has a low predictive value for the development of thyroid hypofunction during the indicated surveillance period. Longer follow-up is needed.

Thyrotropin-stimulating hormone receptor gene analysis in pediatric patients with non-autoimmune subclinical hypothyroidism.

CONTEXT: Mutations in TSH receptor (TSHR) are notoriously associated with congenital hypothyroidism as well as with non-autoimmune subclinical hypothyroidism, a mild form of TSH resistance that is not as well characterized by diagnostic procedures. OBJECTIVE: The genetic analysis of the TSHR gene was performed to determine the prevalence of TSHR gene mutations in non-autoimmune subclinical hypothyroidism during the pediatric age. The new mutations were studied for genotypic-phenotypic correlation. PATIENTS: Thirty-eight children (ages 0.5-18.0 yr) affected by non-autoimmune subclinical hypothyroidism diagnosed in our center (follow-up from 1 to 11.5 yr) and normal at neonatal screening were enrolled in the genetic study. In 11 cases, the relatives were included in the genetic analysis. RESULTS: Eleven different mutations of the TSHR gene were identified in 11 of the 38 patients. Two are new: the nonsense mutation C31X and the missense mutation P68S, which shows a decrease in TSH binding capacity but not in biological activity. In all cases the carrier parent was identified. CONCLUSIONS: To date, this study demonstrates the highest prevalence (29%) of TSHR gene mutations in children and adolescents with non-autoimmune subclinical hypothyroidism not selected by neonatal screening. Functional studies show that some mutations cause a slight inactivation of the TSHR. This reveals a possible limit of the in vitro study or of the knowledge of mechanisms involving TSHR, or that other candidate genes must be considered.

Prospective evaluation of the natural course of idiopathic subclinical hypothyroidism in childhood and adolescence.

OBJECTIVE: To prospectively evaluate the course of subclinical hypothyroidism (SH) in children and adolescents with no underlying diseases and no risk factors, which might interfere with the progression of SH. DESIGN: Clinical status, thyroid function, and autoimmunity were prospectively evaluated at entry and after 6, 12, and 24 months in 92 young patients (mean age 8.1+/-3.0 years) with idiopathic SH. RESULTS: During the study, mean TSH levels showed a trend toward a progressive decrease while FT(4) levels remained unchanged. Overall, 38 patients normalized their TSH (group A): 16 patients between 6 and 12 months, and 22 patients between 12 and 24 months. Among the remaining 54 patients, the majority maintained TSH within the baseline values (group B), whereas 11 exhibited a further increase in TSH above 10 mU/l (group C). Baseline TSH and FT(4) levels were similar in the patients who normalized TSH, compared with those with persistent hyperthyrotropinemia. Even in the patients of group C, both TSH and FT(4) at entry were not different with respect to those of groups A and B. No patients showed any symptoms of hypothyroidism during follow-up and no changes in both height and body mass index were observed throughout the observation period. CONCLUSIONS: (a) The natural course of TSH values in a pediatric population with idiopathic SH is characterized by a progressive decrease over time; (b) the majority of patients (88%) normalized or maintained unchanged their TSH; and (c) TSH changes were not associated with either FT(4) values or clinical status or auxological parameters.

Thyroid nodules and cancer in children and adolescents affected by autoimmune thyroiditis.

OBJECTIVE: To investigate the association between juvenile autoimmune thyroiditis (JAT) and thyroid cancer in pediatric patients. DESIGN: We conducted a retrospective study among children and adolescents affected by JAT. SETTINGS: Data from 6 Italian pediatric endocrinology centers were collected. PARTICIPANTS: Three hundred sixty-five children and adolescents affected by JAT diagnosed at 3.6 to 17.0 years of age. INTERVENTIONS: All patients underwent clinical examination and thyroid function test every 6 to 12 months and thyroid echography every 12 to 24 months. Fine-needle aspiration biopsy was performed in 39 patients with nodule diameter of 1 cm or larger, as well as in 4 patients with nodule diameter of less than 1 cm and echographic findings suspicious for neoplasm. Twenty-three patients underwent surgery. MAIN OUTCOME MEASURES: Thyroid function, echographic pattern, nodule diameter, the presence of lymphadenopathy, and cytologic and histologic diagnoses were considered. RESULTS: Thyroid nodules were found in 115 patients; findings in 11 of these were consistent with papillary carcinoma, with 5 exhibiting lymph node metastasis. The prevalence of male sex among patients with cancer was greater than that among patients with JAT (odds ratio [OR], 2.95; 95% confidence interval [CI], 1.44-6.20). The growth of nodules during levothyroxine sodium therapy (OR, 15.60; 95% CI, 1.87-181.90) and the finding of lymphadenopathy (OR, 5.44; 95% CI, 1.05-30.50) were statistically significantly associated with the presence of cancer, while uninodularity and hypoechogenicity were not. CONCLUSIONS: The observed prevalences of thyroid nodules and thyroid cancer in our JAT case series were 31.5% and 3.0%, respectively. Papillary carcinoma was the only histotype detected. The finding of lymphadenopathy, a lack of response to levothyroxine therapy, and nodule hypoechogenicity suggested malignancy. Fine-needle aspiration biopsy was reliable in selecting patients for referral to surgery.

Reproductive outcome in patients treated and not treated for idiopathic early puberty: long-term results of a randomized trial in adults.

OBJECTIVE: To evaluate the adult reproductive outcome in girls with early puberty who participated in a previous random study. STUDY DESIGN: A total of 22 subjects treated with triptorelin 3.75 mg every 4 weeks (group 1), 18 subjects not treated (group 2), and 22 age-matched normal volunteers (control group) underwent a physical examination, serum hormone level determination, and pelvic ultrasonography. RESULTS: The characteristics of menstrual cycles, serum hormone levels, and ultrasound results did not differ significantly among the 3 groups examined. The mean ovarian volume and the uterine volume tended to increase in the subjects of group 2, but the differences were not significant. The percentage of subjects who reported being sexually active at the time of the examination was greater in the 2 groups with previous early puberty than in the controls (76% of cases in group 1, 72% in group 2, and 59% in the control group). CONCLUSIONS: Neither early puberty nor its treatment seems to significantly affect the normal adult function of the pituitary-gonadal axis.

Effect on adult height of pubertal growth hormone retesting and withdrawal of therapy in patients with previously diagnosed growth hormone deficiency.

CONTEXT: GH replacement therapy in GH-deficient (GHD) patients is usually continued until adult height despite the fact that most of these subjects display a normal secretion when retested at the end of growth. Puberty is the most likely time for normalization of GH secretion. OBJECTIVES: The objectives of this study are to establish the characteristics and the percentage of the subjects with isolated GHD who normalized secretion at puberty and to compare their statural outcomes with those of the subjects with persistent deficiency treated also after retesting. DESIGN AND SETTING: This was a prospective, nonrandomized, open-label study conducted in a university research hospital. PATIENTS AND INTERVENTION: Sixty-nine subjects (40 male, 29 female) with a diagnosis before puberty of isolated GHD by means of arginine and l-dopa tests were reevaluated with the same tests after at least 2 yr of therapy and after puberty onset. If GH peak at retesting was more than 10 microg/liter, therapy was withdrawn. MAIN OUTCOME MEASURES: Percentage and characteristics of normalized subjects at retesting, outcome of treatment in the subjects treated or untreated to adult height, and factors predictive of growth outcome were measured. RESULTS: At retesting, 44 subjects (63.7%) confirmed a GH peak less than 10 microg/liter (24 of 40 male and 20 of 29 female). Apart from a less delayed bone age at diagnosis in females, the subjects with confirmed GHD were not different at diagnosis from the other group for height deficit at diagnosis, first year growth response to GH, age and height at puberty onset, height, and IGF-I at retesting. Mean adult height was 165.1 +/- 4.5 cm in the male group treated until adult height vs. 164.0 +/- 3.4 cm in the group who suspended therapy at retesting. Mean adult height was 153.2 +/- 4.1 cm in the female group treated until adult height vs. 152.9 +/- 5.2 cm in the group that suspended therapy at retesting. As regards the parameters expressing the final outcome, the only difference was found in the mean increment adult height-target height sd score in favor of the male group treated until adult height. In both sexes, therapy duration and GH levels at diagnosis and at retesting were unrelated to adult height parameters and to height increments during the period of observation. CONCLUSIONS: One third of our GHD subjects diagnosed before puberty presented a normal secretion at puberty. The withdrawal of GH therapy in these subjects after retesting was not associated with a catch down growth, and they obtained an adult height similar to those obtained by the GHD subjects treated until adult height. It seems convenient, in subjects with nonsevere GHD, to retest GH secretion at midpuberty and to withdraw treatment for the subjects that are no longer deficient.

CYP21 genotype, adult height, and pubertal development in 55 patients treated for 21-hydroxylase deficiency.

In a retrospective study we evaluated long-term growth, pubertal developmental patterns to final height (FH), and medication in 55 patients (35 females) affected by 21-hydroxylase deficiency. The patients were classified into 3 groups according to predicted mutation severity: group A (11 women and 9 men), homozygous or compound heterozygous for null or In2 splice mutations [residual enzymatic activity (RA), <1%]; group B (11 women and 4 men), homozygous for I172N or R341P or R426H mutations (RA, approximately 2-3%) or compound heterozygous with any of the group A or B mutations; and group C (13 women and 7 men), homozygous for P30L or V281L or P453S mutations (RA, >30%) or compound heterozygous with any of the group A, B, or C mutations. Three patients showed unclassifiable genotypes. FH was similar in the female groups, whereas male patients in group B were shorter than males in groups A and C. Fifty-five percent of patients in group A, 33% in group B, and 40% in group C reached an FH within 0.5 SD of target height. Four of the 7 patients diagnosed via neonatal screening achieved an FH equal to or above the target height. In the entire group, early diagnosis (<1 yr) improved height outcome. Early diagnosed CAH patients who received lower cortisol equivalent doses during the first year of life reached a better FH. Our results underline the importance of mineralocorticoid therapy, as CAH subjects in groups A and B who did not receive this treatment showed reduced FH. Early diagnosis, the use of more physiological cortisol equivalent dosages during the first year of life, and the extension of mineralocorticoid therapy to all classical patients are shown to improve the auxological outcome. Genotypic analysis helped to interpret the height results of our cases and prospectively may represent a useful tool for improving the therapeutic choice and the height outcome.

Treatment for congenital hypothyroidism: thyroxine alone or thyroxine plus triiodothyronine?

OBJECTIVE: To compare the effects of therapy with thyroxine (T4) plus triiodothyronine (T3) versus T4 alone from the first days of life in screened congenital hypothyroid (CH) infants. METHODS: We examined 14 CH infants diagnosed by neonatal screening and a group of control infants. CH patients were divided randomly into 2 groups, 1 treated with T4 alone (group 1) and the other treated with T4 plus T3 (liothyronine; group 2). In all patients electrocardiography and thyroid hormone evaluations were performed before and 15 and 30 days and 3, 6, and 12 months after the beginning of therapy. Psychological tests were also performed at 6 and 12 months of age in CH patients and in other matched controls. RESULTS: After 15 days of treatment, serum thyrotropin (TSH) levels become normal in 5 of 7 cases of group 1 (median TSH level 10.7 micro U/ml) and in 1 of 7 cases of group 2 (median TSH level 72.5 micro U/ml). At the same period, serum-free thyroid hormone levels were within the normal range in both groups, but free T4 values were significantly higher in group 1 than in group 2 and in controls. At the subsequent examinations, free T4 values were within the upper normal limit in group 1, whereas they remained within the normal range in group 2. No clinical or electrocardiographic signs of heart disease were found in any of the patients. The psychometric quotient in CH infants was significantly lower than in controls, but similar in patients of group 1 and group 2. CONCLUSIONS: The combined treatment with T4 plus T3 seems not to show significant advantages, at least in our experimental conditions, compared with the traditional treatment with T4 alone in early treated CH infants. A further longer and more extensive follow-up is mandatory.