Search

Objectives: To report an unusual case of MCT8 deficiency (Allan-Herndon-Dudley syndrome), an X-linked condition caused by pathogenic variants in the SLC16A2 gene. Defective transport of thyroid hormones (THs) in this condition leads to severe neurodevelopmental impairment in males, while heterozygous females are usually asymptomatic or have mild TH abnormalities., Case Presentation: A girl with profound developmental delay, epilepsy, primary amenorrhea, elevated T3, low T4 and free T4 levels was diagnosed with MCT8-deficiency at age 17 years, during evaluation for primary ovarian insufficiency (POI). Cytogenetic analysis demonstrated balanced t(X;16)(q13.2;q12.1) translocation with a breakpoint disrupting SLC16A2. X-chromosome inactivation studies revealed a skewed inactivation of the normal X chromosome., Conclusions: MCT8-deficiency can manifest clinically and phenotypically in women with SLC16A2 aberrations when nonrandom X inactivation occurs, while lack of X chromosome integrity due to translocation can cause POI., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

Objectives: Although AVP and its surrogate, copeptin, are mainly regulated by osmotic and volume stimuli, their secretion is also elicited by stress and growth hormone (GH) stimulating agents. The aim of this report is to describe unusual patterns of copeptin response in a subset of children undergoing GH stimulation tests (GH-ST)., Methods: We conducted a secondary analysis of a cohort of 93 healthy short children with no polydipsia, polyuria or fluid/electrolyte abnormalities, undergoing GH-ST with intravenous arginine, insulin, oral clonidine, or L-Dopa/carbidopa in various combinations. Serum copeptin concentrations were measured 1-3 min after phlebotomy (0 min) and at 60, 90, 120 min during GH-ST., Results: In 85 subjects (normal response group, NRG) serum copeptin concentrations increased from a 0 min median of 9 pmol/L (IQR 6, 11.5) (all values ≤21) to a median peak between 60 and 120 min of 22 (IQR15, 38) pmol/L, which varied depending on the stimulating agent. Conversely, in the eight outliers, copeptin concentrations decreased gradually from a median of 154 (IQR 61, 439) pmol/L (all ≥40 pmol/L) to values as low as 14 % of the basal value, by 120 min. Test-associated anxiety was described in 17 subjects in the NRG (20 %) and five of the outliers (63 %)., Conclusions: A distinctive pattern of very elevated serum copeptin concentrations occurred in 9 % of children undergoing GH-ST, similar to reports in previous pediatric studies. Etiology may include pain or stress of phlebotomy. This phenomenon should be recognized for proper interpretation of copeptin values in children., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)

Importance: Appropriately established pediatric reference intervals are critical to the clinical decision-making process and should reflect the physiologic changes that occur during healthy child development. Reference intervals used in pediatric care today remain highly inconsistent across a broad range of common clinical biomarkers., Observations: This narrative review assesses biomarker-specific pediatric reference intervals and their clinical utility with respect to the underlying biological changes occurring during development. Pediatric reference intervals from PubMed-indexed articles published from January 2015 to April 2021, commercial laboratory websites, study cohorts, and pediatric reference interval books were all examined. Although large numbers of pediatric reference intervals are published for some biomarkers, very few are used by clinical and commercial laboratories. The patterns, extent, and timing of biomarker changes are highly variable, particularly during developmental stages with rapid physiologic changes. However, many pediatric reference intervals do not capture these changes and thus do not accurately reflect the underlying biochemistry of development, resulting in significant inconsistencies between reference intervals., Conclusions and Relevance: There is a need to correctly describe the biochemistry of child development as well as to identify strategies to develop accurate and consistent pediatric reference intervals for improved pediatric care.

Context: Patients with mutations in thyroid hormone transporter MCT8 have developmental delay and chronic thyrotoxicosis associated with being underweight and having cardiovascular dysfunction., Objective: Our previous trial showed improvement of key clinical and biochemical features during 1-year treatment with the T3 analogue Triac, but long-term follow-up data are needed., Methods: In this real-life retrospective cohort study, we investigated the efficacy of Triac in MCT8-deficient patients in 33 sites. The primary endpoint was change in serum T3 concentrations from baseline to last available measurement. Secondary endpoints were changes in other thyroid parameters, anthropometric parameters, heart rate, and biochemical markers of thyroid hormone action., Results: From October 15, 2014 to January 1, 2021, 67 patients (median baseline age 4.6 years; range, 0.5-66) were treated up to 6 years (median 2.2 years; range, 0.2-6.2). Mean T3 concentrations decreased from 4.58 (SD 1.11) to 1.66 (0.69) nmol/L (mean decrease 2.92 nmol/L; 95% CI, 2.61-3.23; P < 0.0001; target 1.4-2.5 nmol/L). Body-weight-for-age exceeded that of untreated historical controls (mean difference 0.72 SD; 95% CI, 0.36-1.09; P = 0.0002). Heart-rate-for-age decreased (mean difference 0.64 SD; 95% CI, 0.29-0.98; P = 0.0005). SHBG concentrations decreased from 245 (99) to 209 (92) nmol/L (mean decrease 36 nmol/L; 95% CI, 16-57; P = 0.0008). Mean creatinine concentrations increased from 32 (11) to 39 (13) µmol/L (mean increase 7 µmol/L; 95% CI, 6-9; P < 0.0001). Mean creatine kinase concentrations did not significantly change. No drug-related severe adverse events were reported., Conclusions: Key features were sustainably alleviated in patients with MCT8 deficiency across all ages, highlighting the real-life potential of Triac for MCT8 deficiency., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Endocrine Society.)

Childhood cases of myxedema coma are extremely rare. We report a case of a 5-year-old girl transferred to a tertiary care pediatric emergency department with hypoxemia and altered mental status and diagnosed with severe hypothyroidism and myxedema coma in the setting of acute influenza infection. Although it is rare, myxedema coma must remain in the differential diagnosis for altered mental status and organ dysfunction in the pediatric population.

Isolated glucocorticoid deficiency (IGD) is an autosomal recessive disorder characterized by primary adrenocortical insufficiency, without mineralocorticoid deficiency. Mutations of the ACTH receptor gene have been reported in several families with IGD. We have amplified and directly sequenced the entire intronless ACTH receptor gene in a new family with IGD. The proband was found to be compound heterozygote for two different point mutations, one in each allele: (a) a substitution (360C>G) which changed neutral serine at position 120 in the apolar third transmembrane domain of the receptor to a positively charged arginine (S120R), probably disrupting the ligand-binding site; and (b) a substitution (761A>G) changing tyrosine at position 254 to cysteine (Y254C) in the third extracellular loop of the receptor protein, that also likely disrupts its structure and interferes with ligand binding. Each of the two mutations in the proband has previously been described in a different family, S120R in compound heterozygosity with a stop codon (R201X) and Y254C in homozygote form. Thus, in the absence of in vitro functional studies, our findings confirm the pathogenetic role of the S120R and Y254C mutants in the development of resistance to ACTH., (Copyright 2000 Academic Press.)

Objective: The diagnostic significance of an enlarged pituitary gland regarding both shape and size parameters on MR imaging has previously been demonstrated in children with central precocious puberty. This study was designed to assess changes in these parameters following successful suppressive therapy of central precocious puberty with the gonadotropin-releasing hormone (GnRH) analogue., Materials and Methods: Twelve girls (mean age 7.3 years) with central precocious puberty were prospectively enrolled in our study protocol. Sagittal and coronal MR images of the pituitary region were obtained in all patients before treatment and after at least 6 months of GnRH analogue therapy (mean 18.0 months). Parameters measured included pituitary gland height, length, width, sagittal cross-sectional area, and volume., Results: All patients had excellent clinical response to treatment with arrest of secondary sexual development, normalization of serum estradiol levels, and complete obliteration of the LH response to diagnostic GnRH stimulation. No significant change occurred in any pituitary size or shape parameter following GnRH analogue therapy., Conclusion: Favorable clinical response to GnRH analogue therapy in central precocious puberty is not accompanied by significant a change in pituitary gland size and shape.

To date the molecular basis and hormonal criteria for inherited mild late-onset 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) deficiency congenital adrenal hyperplasia (CAH) have not been defined. We have thus investigated the presence or absence of mutation in the type II 3 beta-HSD gene encoding adrenal/gonadal 3 beta-HSD in each of five premature pubarche children and hirsute female patients manifesting moderately decreased adrenal 3 beta-HSD activity. ACTH-stimulated hormonal levels in all patients compared with mean levels in pubertal stage-matched normal subjects were between 2.5 and 6.5 SD for 17-hydroxypregnenolone levels, and between 2.5 and 7 SD for dehydroepiandrosterone levels in all except one patient. 17-Hydroxypregnenolone to cortisol ratios were between 2.5 and 4.3 SD, and dehydroepiandrosterone to androstenedione ratios were between 3 and 8.6 SD. The type II 3 beta-HSD gene regions of a putative promoter, exons I, II, III, and IV, and exon-intron boundaries in all subjects were amplified by polymerase chain reaction and then sequenced. All patients had normal sequences of the type II 3 beta-HSD gene in both alleles. Three female patients heterozygotic for severe 3 beta-HSD deficiency CAH with one allele mutation of the gene demonstrated normal ACTH-stimulated hormone profiles. These data indicate that moderately decreased adrenal 3 beta-HSD activity resulting in modestly increased delta 5 precursor steroid levels and delta 5 to delta 4 steroid ratios in premature pubarche and hirsute patients is not caused by a mutation in the type II 3 beta-HSD gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Objective: Central precocious puberty occurs as a result of premature pituitary stimulation and increased secretion of gonadotropins. The aims of this study were to analyze MR imaging findings in the pituitary glands of children with central precocious puberty compared with matched control subjects, to define MR imaging-derived variables useful in the diagnosis of central precocious puberty, and to correlate MR imaging-derived variables with the hormonal profile and other imaging and clinical findings., Materials and Methods: Twenty-six children with central precocious puberty (two boys and 24 girls) were divided into two subgroups according to MR imaging findings: idiopathic (21 patients) and nonidiopathic (five patients: three hypothalamic hamartomas, one pineal tumor, one empty sella syndrome). The control group consisted of 17 normal age- and sex-matched children (two boys, 15 girls). Analyzed parameters included pituitary height, length, width, midsagittal cross-sectional area, calculated volume, and shape. The shape was assessed by a pituitary grading system and two other shape indexes (length-to-height and length-to-width ratios). Pituitary grade was defined by the concavity of the upper pituitary surface (grade 1 = marked concavity, grade 2 = mild concavity, grade 3 = flat, grade 4 = mild convexity, grade 5 = marked convexity)., Results: Pituitary grade showed a highly significant difference among groups (p < .001). Area, height, and length-to-height ratio were significantly different (p < .05), whereas length, width, length-to-width ratio, and volume were not. There was no significant difference in any of the variables compared between idiopathic and nonidiopathic groups. When selected variables (pituitary grade, area, height, length) in the central precocious puberty group were stratified by bone age and findings on pelvic sonograms, patients with advanced bone age had a significantly higher pituitary grade (p < .01) and had a tendency toward a greater pituitary length. Pituitary size and shape correlated with the hormonal profile., Conclusion: Change in pituitary grade is the most helpful variable for the diagnosis of central precocious puberty in a prepubertal child. A high pituitary grade (4 or above) is highly predictive of central precocious puberty, with the highest specificity and positive predictive value, but with low sensitivity. The use of combinations of high pituitary grade with two other positive findings (height and area greater than 1 SD from the respective means in the control group) improves the sensitivity, specificity, and predictive value of MR imaging in the diagnosis of central precocious puberty.

Purpose: To assess the dynamics of the pituitary-ovarian axis in exaggerated thelarche, defined as premature thelarche associated with signs of systemic estrogen effects (advanced bone age and/or growth acceleration) without progression to complete puberty., Subjects and Methods: Seven girls (age < 2.5 years) with exaggerated thelarche, 6 girls with inactive pituitary-ovarian axis (premature adrenarche) and 21 girls with activated axis (central precocious puberty) had serum FSH, LH and E2 measured serially before and 1 to 24 h after gonadotropin-releasing hormone agonist (GnRHa) administration (leuprolide, 20 micrograms/kg sc), used as a test of combined pituitary-ovarian stimulation., Results: Although girls in the exaggerated thelarche and adrenarche group had similar [mean (SEM)] baseline FSH [3.2 (0.9) vs 1.4 (0.3) IU/l], LH [0.36 (0.1) vs 0.27 (0.02) IU/l] and E2 [20 (1.2) vs 21 (2) pmol/l] concentrations, and similar peak post-GnRHa LH concentrations [5.5 (1.1) vs 2.4 (0.5) IU/l], girls with exaggerated thelarche achieved higher peak FSH [41 (9) vs 14 (3) IU/l, p < 0.01] and E2 [243 (40) vs 37 (6) pmol/l, p < 0.001] concentrations after GnRHa. In comparison to patients with exaggerated thelarche, girls with precocious puberty had higher (p < 0.01-0.001) baseline LH [3.6 (0.8) IU/l], baseline E2 [69(11) pmol/l], GnRHa-stimulated peak LH [68 (17) IU/l] and peak E2 [648 (58) pmol/l] concentrations, but similar FSH parameters., Conclusions: Girls with exaggerated thelarche exhibit substantial E2 secretory potential that can be demonstrated by GnRHa stimulation, is predominantly FSH-driven, and probably accounts for the manifestations of estrogen effect seen in these girls.

We used the GnRH agonist (GnRHa) stimulation test (20 micrograms/kg leuprolide sc, followed by 24-h serial sampling) to investigate the relationship between gonadotropin and estradiol (E2) secretion in the early phase of female central precocious puberty (CPP). Girls with CPP and moderately increased (early pubertal) peak E2 concentrations after GnRHa stimulation (136 +/- 11 pmol/L; range, 92-176; group B; n = 7) were compared to girls with CPP and higher (midpubertal) peak E2 responses to GnRHa (mean +/- SE, 590 +/- 63 pmol/L; range, 235-1189; group C; n = 19) and to a group of subjects with no breast development and a prepubertal hypothalamic-pituitary-gonadal axis (peak E2 response to GnRHa, 39 +/- 7 pM/L; range, 18-62; group A; n = 6). Compared to group A subjects, patients in group B had similar (P > 0.2) peak GnRHa-stimulated LH concentrations (B, 4.8 +/- 1 IU/L; A, 2.3 +/- 0.5 IU/L) and peak nocturnal LH (B, 0.81 +/- 0.2; A, 0.25 +/- 0 IU/L), but higher peak GnRHa-stimulated FSH concentrations (B, 26 +/- 7; A, 11 +/- 2 IU/L; P < 0.05) and mean nocturnal FSH (B, 4.2 +/- 1; A, 1.1 +/- 0.3 IU/L; P < 0.05) concentrations. Compared to group B, group C patients had higher (P < 0.001) GnRHa-stimulated peak LH (67 +/- 19 IU/L) and higher (P < 0.05) peak nocturnal LH (9.7 +/- 2.9 IU/L) concentrations, but similar GnRHa-stimulated peak FSH (27 +/- 3 IU/L) and mean nocturnal FSH (3.8 +/- 0.5 IU/L) levels. Group C patients with a ratio of peak GnRHa-stimulated LH to FSH concentrations below or above 1, respectively, had similar peak E2 responses to GnRHa (516 +/- 80 vs. 644 +/- 92 pM/L; P > 0.1). Stepwise regression analysis indicated that the peak LH response to GnRHa (r = 0.76; P < 0.001), but none of the FSH secretory parameters (P > 0.10), affected the E2 response to GnRHa. These data suggest that girls with CPP in the early phase of activation of the hypothalamic-pituitary-gonadal axis are capable of clinically relevant E2 production, which may occur in the face of low LH secretion and low LH/FSH ratios and cannot be explained solely on the basis of increased FSH secretion. Thus, endocrine or paracrine factors other than gonadotropins may be important in amplifying E2 secretion in the early phase of CPP.

To determine the diagnostic potential of a highly sensitive immunoradiometric assay (IRMA) for LH in children with normal puberty or altered tempo of sexual maturation, we compared serum LH levels by IRMA (LH IRMA) and standard RIA (LH RIA) in children with idiopathic precocious thelarche (IPT; n = 6), idiopathic premature adrenarche (IPA; n = 14), central precocious puberty (CPP; n = 15), and constitutional delay of puberty (DP; n = 15), and 160 control children (79 males and 81 females). Subjects in the latter group were staged, according to their genital or breast development, as early prepubertal (P1E; age, less than 8 yr), late prepubertal (P1L; 8-12 yr), or stage II-V (P2-P5; n = 22-34 for each subgroup). Serum LH IRMA levels in P1E, IPT, and IPA children were either undetectable (95% of subjects less than 0.25 IU/L) or barely detectable (5% of subjects, less than or equal to 0.5 IU/L). Serum LH IRMA levels were greater than 0.5 IU/L in 38% of P1L (mean +/- SD for the group, 1.0 +/- 1.3 IU/L) and 57% of P2 (1.4 +/- 1.3 IU/L); they were greater than 1.0 IU/L in 100% of P3 (2.6 +/- 1.3 IU/L), P4 (3.9 +/- 2 IU/L), and P5 (8.6 +/- 4 IU/L) children. Comparison of serum LH levels between contiguous pubertal stages showed significantly higher LH IRMA concentrations in P3 vs. P1E, P4 vs. P2, P5 vs. P4 (all P less than 0.001), and P3 vs. P1L (P less than 0.05). In contrast, LH RIA values were not significantly different in P1E (2.0 +/- 0.6 IU/L), P1L (2.3 +/- 0.6 IU/L), P2 (2.7 +/- 0.9 IU/L), P3 (3.2 +/- 1.3 IU/L), and P4 (3.7 +/- 2.2 IU/L), although they were higher in P5 (6.8 +/- 4 IU/L) than in P4 (P less than 0.001). From P1E to P5 LH IRMA levels increased 38-fold in females and 21-fold in males, while LH RIA increased 4- and 2.1-fold, respectively. Serum LH IRMA correlated significantly with serum testosterone levels in boys from P1L to P5 (r = 0.76; P less than 0.001), while LH RIA levels did not (r = 0.18). Serum LH IRMA concentrations were above the prepubertal range (greater than 0.5 IU/L) in 67% of children with CPP (group average, 1.8 +/- 1.4 IU/L) and 87% of children with DP (1.6 +/- 1.4 IU/L).(ABSTRACT TRUNCATED AT 400 WORDS)

To investigate the role of adrenal androgens in 3 alpha-androstanediol glucuronide (3AG) production in childhood, we compared serum 3AG and androgen levels [dehydroepiandrosterone (DHEA), DHEA sulfate (DS), androstenedione (delta 4-A), and testosterone (T)] in 32 children with premature pubarche due to idiopathic premature adrenarche (IPA; n = 26), partial 21-hydroxylase deficiency (n = 2), or 3 beta-hydroxysteroid dehydrogenase deficiency (n = 4) with those in 36 normal prepubertal (18 males and 18 females) and 22 normal pubertal Tanner II-III subjects (10 males and 12 females). Serum 3AG (2.7 +/- 2.0 nmol/L) and all androgen concentrations in children with IPA were significantly higher (P less than 0.05-0.001) than those in normal prepubertal children (3AG, 0.8 +/- 0.5 nmol/L). Serum 3AG and androgen levels, except T, in all children with premature pubarche due to 21-hydroxylase deficiency or 3 beta-hydroxysteroid dehydrogenase deficiency were higher than those in the normal prepubertal children. Serum 3AG and all androgen levels in normal Tanner II-III male (3AG, 3.8 +/- 1.7 nmol/L) or female (3AG, 1.74 +/- 0.52 nmol/L) subjects were also significantly higher (P less than 0.05-0.001) than those in prepubertal children. Serum 3AG, DHEA, DS, and delta 4-A levels in children with IPA were similar to those in normal Tanner II-III females or males, but serum T in children with IPA (0.37 +/- 0.2 nmol/L) was significantly lower (P less than 0.05-0.001) than that in normal pubertal females (0.71 +/- 0.37 nmol/L) or males (4.5 +/- 2.6 nmol/L). In the combined group (n = 88), 3AG levels correlated better with serum DS (r = 0.7), DHEA (r = 0.6), and delta 4-A (r = 0.52), than with T (r = 0.31) levels. These data suggest that the weak adrenal androgens DS, DHEA, and delta 4-A contribute substantially to 3AG production in premature and normal pubarche.

We evaluated a GnRH agonist (GnRHa) as a potential single stimulus to both pituitary and ovarian secretion in 13 girls with true precocious puberty. We compared the GnRH agonist [6-D-(2-naphthyl)alanine]GnRH acetate (nafarelin, Syntex) administered as a single sc injection of 0.2 microgram/kg to GnRH infused iv in a dose of 2 micrograms/kg X h for 3 h and assessed the response of plasma steroid intermediates in estradiol (E2) biosynthesis. Although serum LH and FSH levels increased to similar peaks 3 h after commencing GnRH and nafarelin testing, they rose faster (P less than 0.01 at 1 h) and remained elevated longer (P less than 0.05 at 24 h) after nafarelin administration. At the third hour of testing with either agent, LH and FSH rose 8.8- and 3.4-fold, respectively (P less than 0.001 vs. baseline), whereas the rise in E2 was inconsistent and averaged only one third (P less than 0.02). However, plasma E2 increased later after nafarelin, but not after GnRH, rising from a baseline level of 30 +/- 6 (+/- SEM) to 115 +/- 13 pg/ml at 24 h (P less than 0.001). The least E2 response to nafarelin at this time was 150%. This rise is probably an underestimate of the maximum E2 rise, since a 6-fold response to nafarelin was found at 12 h in patients sampled then. Measurement of steroid intermediates from progesterone and 17 alpha-hydroxypregnenolone to E2 indicated that the response to nafarelin was typical of normal ovarian follicular secretion. That is, plasma levels of the intermediates in E2 biosynthesis rose less than 2-fold, and only the elevations in androstenedione, from 58 +/- 10 to 78 +/- 16 ng/dl (P less than 0.05), and estrone, from 14 +/- 3 to 38 +/- 7 pg/ml (P less than 0.02), at 24 h were significant. The greater effectiveness of nafarelin than GnRH in stimulating E2 secretion appears to be related to the more prolonged gonadotropin response. The magnitude, consistency, specificity, and rapidity of the gonadotropin and E2 responses to nafarelin indicate that this is a promising agent for rapidly testing pituitary and ovarian function simultaneously.

Clinical and biochemical evidence of oculocutaneous tyrosinosis, a rare disease due to hepatic soluble tyrosine aminotransferase (STAT) deficiency, was found in a 3 1/2-year-old girl and in her maternal aunt. Different expressivity of this disease, resulting in clinical heterogeneity, is shown to occur commonly according to the cases reported in this as well as in previous studies. The metabolic pathways leading to the unexpected excretion of phenolic acids in urine are reviewed, and the need for early diagnosis and dietary treatment, in order to prevent corneal clouding and brain damage is finally stressed.

Serum concentrations of dehydroepiandrosterone sulfate (DHEAS) were measured in 28 patients (18 females, 10 males) with congenital adrenal hyperplasia due to 21-hydroxylase deficiency who were treated with oral hydrocortisone (non-salt losers) or hydrocortisone and 9-alpha-fluorohydrocortisone (salt-losers). Adequacy of therapy was assessed by clinical findings, determination of bone age, urinary excretion of 17-ketosteroids, and serum concentration of 17-hydroxyprogesterone. These allowed the separation of patients into three groups: poorly controlled, adequately controlled and overtreated. Individual values for serum levels of DHEAS were compared to mean normal values for age. In the adequately controlled and overtreated patients, mean serum concentrations of DHEAS were significantly lower than normal values for age (P less than 0.05). In the poorly treated patients, the mean serum concentration of DHEAS was not significantly different from normal values for age (P = 0.50). These data indicate that the serum concentration of DHEAS is overly suppressed in treated patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. This finding suggests that measurement of the serum levels of DHEAS has limited value in assessing the adequacy of therapy in this disease.

Four boys, aged 2 years 5 months to 3 years 7 months, with large hepatomegaly due to phosphorylase-kinase deficiency glycogenosis, were given a trial of sodium dextrothyroxine (D-T4) at a mean dose of 0.165 mg/kg/day for an average period of 6 months. Phosphorylase-kinase was undetectable in the haemolysates of erythrocytes (3 patients) or in the liver (one patient) before, and still undetectable in the haemolysates of the four patients during treatment, thus pointing to X-linked phosphorylase-kinase deficiency glycogen storage disease (GSD IXb). D-T4 administration resulted in complete normalization of liver size, decrease of serum GOT (p less than 0.02), GPT (p less than 0.05) and triglycerides (p less than 0.01) to normal values, as well as correction of mild asymptomatic hypoglycemia (p less than 0.01). As long as the outcome of type IXb glycogenosis in adult life remains undefined, dextrothyroxine therapy seems an effective means of reducing liver size and correcting part of the biochemical abnormalities of the disease.