Biochemical monitoring of 21-hydroxylase deficiency: a clinical utility of overnight fasting urine pregnanetriol.

PURPOSE OF REVIEW: 21-Hydroxylase deficiency (21-OHD), the most common form of congenital adrenal hyperplasia, is an autosomal recessive disorder caused by pathogenic variants in CYP21A2 . Although this disorder has been known for several decades, many challenges related to its monitoring and treatment remain to be addressed. The present review is written to describe an overview of biochemical monitoring of this entity, with particular focus on overnight fasting urine pregnanetriol. RECENT FINDINGS: We have conducted a decade-long research project to investigate methods of monitoring 21-OHD in children. Our latest studies on this topic have recently been published. One is a review of methods for monitoring 21-OHD. The other was to demonstrate that measuring the first morning PT level may be more practical and useful for biochemical monitoring of 21-OHD. The first morning pregnanetriol (PT), which was previously reported to reflect a long-term auxological data during the prepubertal period, correlated more significantly than the other timing PT in this study, with 17-OHP, before the morning medication. SUMMARY: In conclusion, although the optimal method of monitoring this disease is still uncertain, the use of overnight fasting urine pregnanetriol (P3) as a marker of 21-OHD is scientifically sound and may be clinically practical.

Factors associated with low bone mineral density in Turner syndrome: a multicenter prospective observational study.

Turner syndrome (TS) is associated with a high risk of fracture due to low bone mineral density (BMD). While hypogonadism is known to play a role in decreasing BMD, other factors have not been studied well. Focusing on diet, exercise, and bone metabolism markers, the present, multicentric, prospective, observational study aimed to identify factors contributing to decreased BMD in TS. In total, 48 patients with TS aged between 5 and 49 years comprising a pre-pubertal group (n = 9), a cyclical menstruation group (n = 6), and a hormone replacement therapy (HRT) group (n = 33) were enrolled. The cyclical menstruation group and the HRT group were referred to collectively as the post-pubertal group. The bone mineral apparent density (BMAD) Z-score was higher in the pre-pubertal group than in the post-pubertal group (-0.3 SD vs. -1.8 SD; p = 0.014). Within the post-pubertal group, the median BMAD Z-score was -0.2 SD in the cyclical menstruation group and -2.3 SD in the HRT group (p = 0.016). Spearman's rank correlation revealed no correlation between the BMAD Z-score and bone metabolism markers. No significant relationship was observed between the BMAD Z-score and either the vitamin D sufficiency rate or the step sufficiency rate. A negative correlation was found between BMAD Z-score and serum sclerostin in the pre-pubertal group and serum FSH in the post-pubertal group. In conclusion, the present study found no relationship between the vertebral BMAD Z-score and diet or exercise habits in TS, indicating that estrogen deficiency is the chief reason for low BMD in TS.

Detection of multiple druggable mutations of lung cancer from cytology specimens by MINtS: An advanced medicine A trial.

Most multigene mutation tests require tissue specimens. However, cytological specimens are easily obtained in the clinical practice and provide high-quality DNA and RNA. We aimed to establish a test that utilizes cytological specimens and performed a multi-institutional study to investigate the performance of MINtS, a test based on next-generation sequencing. A standard procedure for specimen isolation was defined. The specimens were considered suitable for the test if >100 ng DNA and >50 ng RNA could be extracted from them. In total, 500 specimens from 19 institutions were investigated. MINtS detected druggable mutations in 63% (136 of 222) of adenocarcinomas. Discordant results between MINtS and the companion diagnostics were observed in 14 of 310 specimens for the EGFR gene, and 6 of 339 specimens for the ALK fusion genes. Confirmation by other companion diagnostics for the EGFR mutations or the clinical response to an ALK inhibitor all supported the results obtained by MINtS. MINtS along with the isolation procedure presented in the current study will be a platform to establish multigene mutation tests that utilize cytological specimens. UMIN000040415.

Longitudinal clinical course in patients with 5α-reductase type 2 deficiency treated with testosterone and dihydrotestosterone during infancy and puberty.

5α-reductase type 2 (5αRD2) deficiency is a 46,XY disorder of sex development caused by impaired conversion of testosterone (T) to dihydrotestosterone (DHT). Penile enlargement therapy is important for male patients with 46,XY 5αRD2 deficiency who have undermasculinized external genitalia, such as severe micropenis. High-dose T and percutaneous DHT replacement are reportedly efficacious for penile enlargement in patients with this disorder. We presented herein the longitudinal course of four patients with 46,XY 5αRD2 deficiency who received T and DHT. T replacement therapy during infancy increased the stretched penile length (SPL) in three of the patients but was ineffective in one patient. DHT was administered to the three patients after T replacement therapy and further increased the SPL. During and after puberty, two patients asked for and received T replacement therapy, which contributed to increasing their SPL. A semen test in one patient with T replacement therapy at age 27 years revealed cryptozoospermia despite normal testicular volume. The clinical course of our patients during infancy indicated that DHT therapy may be preferrable to T replacement therapy for penile enlargement in patients with 5αRD2 deficiency. During and after puberty, T replacement therapy promoted penile enlargement possibly because of increased conversion of T to DHT via increased 5α-reductase type 1 activity even in patients in whom it was ineffective during infancy. In conclusion, DHT is effective for penile enlargement during infancy in patients with 5αRD2 deficiency while T replacement therapy is a viable option during puberty.

Optical Genome Mapping for a Patient with a Congenital Disorder and Chromosomal Translocation.

We performed optical genome mapping (OGM), a newly developed cytogenetic technique, for a patient with a disorder of sex development (DSD) and a 46,XX,t(9;11)(p22;p13) karyotype. The results of OGM were validated using other methods. OGM detected a 9;11 reciprocal translocation and successfully mapped its breakpoints to small regions of 0.9-12.3 kb. OGM identified 46 additional small structural variants, only three of which were detected by array-based comparative genomic hybridization. OGM suggested the presence of complex rearrangements on chromosome 10; however, these variants appeared to be artifacts. The 9;11 translocation was unlikely to be associated with DSD, while the pathogenicity of the other structural variants remained unknown. These results indicate that OGM is a powerful tool for detecting and characterizing chromosomal structural variations, although the current methods of OGM data analyses need to be improved.

Identification of clinical factors related to antibody-mediated immune response to the subfornical organ.

OBJECTIVE: We recently reported cases of adipsic hypernatremia caused by autoantibodies against the subfornical organ in patients with hypothalamic-pituitary lesions. This study aimed to clarify the clinical features of newly identified patients with adipsic hypernatremia whose sera displayed immunoreactivity to the mouse subfornical organ. DESIGN: Observational cohort study of patients diagnosed with adipsic hypernatremia in Japan, United States, and Europe. METHODS: The study included 22 patients with adipsic hypernatremia but without overt structural changes in the hypothalamic-pituitary region and congenital disease. Antibody response to the mouse subfornical organ was determined using immunohistochemistry. The clinical characteristics were compared between the patients with positive and negative antibody responses. RESULTS: Antibody response to the mouse subfornical organ was detected in the sera of 16 patients (72.7%, female/male ratio, 1:1, 12 pediatric and 4 adult patients). The prolactin levels at the time of diagnosis were significantly higher in patients with positive subfornical organ (SFO) immunoreactivity than in those with negative SFO immunoreactivity (58.9 ± 33.5 vs. 22.9 ± 13.9 ng/ml, p < .05). Hypothalamic disorders were found in 37.5% of the patients with positive SFO immunoreactivity. Moreover, six patients were diagnosed with rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation/neural tumor syndrome after the diagnosis of adipsic hypernatremia. Plasma renin activity levels were significantly higher in patients with serum immunoreactivity to the Nax channel. CONCLUSIONS: The patients with serum immunoreactivity to the SFO had higher prolactin levels and hypothalamic disorders compared to those without the immunoreactivity. The clinical characteristics of patients with serum immunoreactivity to the subfornical organ included higher prolactin levels and hypothalamic disorders, which were frequently associated with central hypothyroidism and the presence of retroperitoneal tumors.

Current status of transition medicine for 21-hydroxylase deficiency in Japan: from the perspective of pediatric endocrinologists.

To manage of 21-hydroxylase deficiency (21-OHD), transition medicine from pediatric to adult health care is an important process and requires individually optimized approaches. We sent cross-sectional questionnaire surveys on the current status of transition from pediatric to adult health care in 21-OHD patients to all councillors of the Japanese Society for Pediatric Endocrinology. Many pediatric departments (42.2%) experienced adult 21-OHD patients, and 115 patients (53 males, mean age of 26) in 46 institutions were identified. Whereas almost two-thirds of pediatric endocrinologists regarded the problems of counterparts and cooperation as hindrance of transition medicine, the major reason for continuing to be treated in pediatrics was the patient's own request. The prevalence of long-term complications including obesity, osteoporosis, infertility, menstrual disorder, gender dysphoria, and testicular adrenal rest tumor were 27.5%, 8.8%, 11.1%, 26.3%, 7.1%, 12.5%, respectively, which is comparable to those of other cohorts previously reported. However, several items, especially infertility and osteoporosis were not checked well enough in adult 21-OHD patients treated in pediatrics. Though 44 of 62 female patients had genital reconstructive surgery, more than half of them were not followed up by gynecologists or pediatric urologists. Quite a few adult 21-OHD patients had been followed up in pediatrics even after coming of age; however, surveillance by pediatric endocrinologists of gynecological, reproductive, and mental problems may be insufficient. Therefore, multidisciplinary approaches should be required in transition medicine for 21-OHD and prerequisite for graduation of pediatrics. Pediatric endocrinologists will need to play a leading role in the development of transition systems.

Starting age of oestrogen-progestin therapy is negatively associated with bone mineral density in young adults with Turner syndrome independent of age and body mass index.

OBJECTIVE: Osteoporosis is an important health issue in patients with Turner syndrome (TS), and oestrogen sufficiency has been implicated in increased bone mineral density (BMD); however, the impact of the starting age of hormone replacement therapy (HRT) on bone mineral density remains unclear, particularly during young adulthood. DESIGN: A retrospective study from three tertiary care hospitals in Japan. PATIENTS: One hundred and three patients with TS aged between 18 and 30 years of age who underwent dual-energy X-ray absorptiometry. MEASUREMENTS: Anthropometric parameters, lumbar bone mineral density (L-BMD), including areal BMD (aBMD) and volumetric BMD (vBMD), karyotypes, the presence of spontaneous menarche, the starting ages of oestrogen replacement therapy (ERT) and oestrogen-progestin therapy (EPT), and the duration between starting ages of oestrogen replacement therapy and oestrogen-progestin therapy were investigated. vBMD was calculated based on the Kröger method. RESULTS: aBMD was lower in young adults with TS than in an age-matched reference population. L-BMD positively correlated with weight and body mass index (BMI). L-BMD was higher in subjects with spontaneous menarche (N = 22) than in those without. A dose escalation regimen of oestrogen replacement therapy was used in 84% of subjects without spontaneous menarche (N = 81). The starting age of oestrogen replacement therapy and the duration between the starting ages of oestrogen replacement therapy and oestrogen-progestin therapy negatively and independently correlated with aBMD, but not with vBMD, after adjustment with age and BMI. The starting age of oestrogen-progestin therapy negatively correlated with L-BMD independent of age and BMI. CONCLUSIONS: Early introduction of hormone replacement therapy, particularly oestrogen-progestin therapy, is important to accrue better L-BMD in young adults with TS.

Rapid Hypercalciuria Induction With Bone Formation Marker Reduction During Immobilization in Children.

OBJECTIVE: To prospectively examine the occurrence of hypercalciuria and changes in bone metabolite markers in pediatric patients during immobilization. METHODS: In total, 13 children with an orthopedic disease requiring immobilization longer than 2 weeks were enrolled. Blood samples were collected after breakfast. Urine samples were collected at the second voiding after waking. The urine calcium/creatinine (Ca/Cr) ratio and various bone metabolite parameters were measured before and every 1 to 4 weeks after the start of immobilization. RESULTS: The median patient age was 7 years with a range of 2 to 13 years. Orthopedic diseases in the patients were dislocated hip joint (N = 7), slipped capital femoral epiphysis (N = 2), etc. The urine Ca/Cr ratio increased significantly within a week after immobilization (P < .01) and continued to increase for 2 more weeks. Once immobilization ended, the urine Ca/Cr ratio gradually decreased and returned to the normal range approximately 6 weeks after mobility was achieved (P < .01). Serum alkaline phosphatase (ALP) and bone-specific ALP significantly decreased after immobilization began (P < .01). After immobilization ended, the serum ALP returned to preimmobilization levels in 2 to 4 weeks (P < .01). Serum N-terminal telopeptides did not change significantly during immobilization. CONCLUSION: The urine Ca/Cr ratio immediately increased after immobilization. In contrast to adults, bone formation markers in children decreased during immobilization, whereas bone resorption markers did not increase. To our knowledge, this study is the first to examine bone metabolism markers in children during immobilization.

SOX9 is colocalized with paraspeckle protein NONO in cultured murine sertoli cells and features structural characteristics of intrinsically disordered proteins.

This study provides supporting evidence for the association between SOX9 and liquid-liquid phase separation. We show that SOX9 colocalized with a paraspeckle protein NONO in many, but not all, of the immortalized and primary murine Sertoli cells examined. In addition, we confirmed that SOX9 has structural characteristics of intrinsically disordered proteins.

A retrospective multicenter study of bone mineral density in adolescents and adults with Turner syndrome in Japan.

Osteoporosis is one of the clinical features of women with Turner syndrome (TS). The reasons for low bone mineral density (BMD) and increased bone fragility are multifactorial, including estrogen deficiency, X-chromosome abnormalities, and environmental factors. Few, large-scale studies on bone mineral density in either adolescents or adults with TS have been done in Japan. The goal of the present study was to investigate spinal BMD in women with TS, assess its relationship with clinical parameters, especially estrogen replacement therapy, and investigate its longitudinal changes. The spinal BMD and clinical data of 149 Japanese women with TS aged 15 to 49 years who were followed at the four participating hospitals were retrospectively analyzed. The BMD Z-scores of the women with TS ranged from -5.30 to +1.89. Women with TS aged 15-39 years had lower BMD than healthy Japanese women (p < 0.01) while women with spontaneous menstruation had a significantly higher BMD Z-score than those without spontaneous menstruation (-0.73 ± 1.11 vs. -1.67 ± 1.18, p < 0.01). In women without spontaneous menstruation, BMD Z-scores correlated with the duration of their estrogen therapy (r = 0.167, p < 0.01). Women aged 15-39 years with TS had low BMD, which was associated with primary amenorrhea and short estrogen replacement therapy duration.

Language delay and developmental catch-up would be a clinical feature of pseudohypoparathyroidism type 1A during childhood.

Pseudohypoparathyroidism type 1A (PHP1A) is characterized by resistance to multiple hormones, the Albright Hereditary Osteodystrophy phenotype, obesity, and developmental delay. Developmental delay usually appears prior to hypocalcemia due to parathyroid hormone resistance and could be a clinically important feature for early diagnosis of PHP1A. To date, however, the details have not been documented. With regard to developmental delays, we conducted a multicenter retrospective study of 22 PHP1A patients from 18 families who were diagnosed clinically or genetically from 2005 to 2015. For quantitative analysis of their development, we calculated the ratios of the milestone ages of the patients to those in normal reference data. The ratio of the ages with respect to speech development, i.e., speaking a first meaningful word (median: 1.67), was significantly higher than that for gross motor development, walking unassisted (median: 1.34). The ratio of age at stringing a two-word sentence (median: 1.32) was significantly lower than that of saying a first word (median: 1.84). Ten out of 11 (91%) patients exhibited two or three of the following clinical phenotypes: developmental delay, obesity, and hyperthyrotropinemia. These results suggest two possible clinical features of developmental delays in PHP1A patients: developmental delay is more obvious in speech acquisition than in gross motor skills, and speech delays could be attenuated during later childhood. Further, the presence of multiple of three clinical symptoms could be an important indicator to differentiate the diagnosis of PHP1A during early childhood.

Diagnosis of congenital hyperinsulinism: Biochemical profiles during hypoglycemia.

OBJECTIVES: To define the ranges of biochemical markers during hypoglycemia for the diagnosis of congenital hyperinsulinism (CHI), using high sensitivity insulin assays. SUBJECTS: A total of 298 patients with CHI and 58 control patients with non-hyperinsulinemic hypoglycemia, who were diagnosed after 2007. METHODS: The levels of biochemical markers (glucose, insulin, ß-hydroxybutyrate [BHB], free fatty acids [FFA], lactate, ammonia) at the time of hypoglycemia were analyzed along with the maximal glucose infusion rate (GIR) to maintain euglycemia and clinical outcomes. RESULTS: Median levels of blood glucose in patients with CHI and in controls were 30 and 46 mg/dL, while insulin levels were 9.90 and undetectable (<.5) µU/mL, respectively. Similarly, median levels of BHB were 17.5 and 3745 µmol/L, and those of FFA were 270.5 and 2660 µmol/L, respectively. For patients after 5 months, cutoffs of insulin >1.25 µU/mL, BHB < 2000 µmol/L, and FFA < 1248 µmol/L predicted CHI with sensitivities of 97.5, 96.2, and 95.2% and specificities of 84.2, 89.3, and 92.3%, respectively. Maximal GIR in the CHI groups tended to decrease with age. In addition, decreased gestational age, low birth weight, and elevated lactate at hypoglycemia were significantly more common in patients who were off treatment within 100 days without pancreatectomy. CONCLUSIONS: After introduction of high-sensitive assays, the diagnostic value of insulin was improved, allowing for more efficient cutoffs to be set for diagnosis of CHI. Premature birth, low birth weight and elevated lactate might be helpful in predicting early remission of hypoglycemia.

Integrated treatment for autonomic paraneoplastic syndrome improves performance status in a patient with small lung cell carcinoma: a case report.

BACKGROUND: Paraneoplastic neurological syndromes (PNS) are rare disorders associated with cancer and are believed to be immune mediated. Patients with autonomic PNS suffer from variable combinations of parasympathetic and sympathetic failure. Autonomic PNS are usually associated with other PNS, such as encephalomyelitis and sensory neuropathy; however, autonomic symptoms may rarely manifest as PNS symptoms. Autonomic symptoms, therefore, may be overlooked in patients with cancer. CASE PRESENTATION: We described a 65-year-old Japanese man who was diagnosed with autonomic PNS due to small-cell lung carcinoma (SCLC) with Eastern Cooperative Oncology Group (ECOG) performance status 3, who suffered from orthostatic hypotension, and urinary retention needing a urethral balloon. Laboratory studies showed decreased levels of noradrenaline, and were positive for anti-ganglionic acetylcholine receptor antibody, type 1 antineuronal nuclear antibody, and sry-like high mobility group box 1 antibody. Nerve conduction evaluations and 123I-metaiodobenzylguanidine myocardial scintigraphy showed no abnormalities. Abdominal contrast-enhanced computed tomography revealed marked colonic distention. The patient's autonomic symptoms resolved following integrated treatment (symptomatic treatment, immunotherapy, and additional chemotherapy) enabling the patient to walk, remove the urethral balloon, and endure further chemotherapy. ECOG performance status remained at 1, 10 months after admission. CONCLUSIONS: Integrated treatment for autonomic PNS may improve autonomic symptoms and ECOG performance status of patients with cancer.

Incidence rate and characteristics of symptomatic vitamin D deficiency in children: a nationwide survey in Japan.

There is concern that vitamin D deficiency is prevalent among children in Japan as well as worldwide. We conducted a nationwide epidemiologic survey of symptomatic vitamin D deficiency to observe its incidence rate among Japanese children. A questionnaire inquiring the number of new patients with vitamin D deficiency rickets and/or hypocalcemia for 3 years was sent to 855 randomly selected hospitals with a pediatrics department in Japan. In this survey, we found that 250 children were diagnosed with symptomatic vitamin D deficiency. The estimated number of patients with symptomatic vitamin D deficiency per year was 183 (95% confidence interval (CI): 145-222). The overall annual incidence rate among children under 15 years of age was 1.1 per 100,000 population (95% CI: 0.9-1.4). The second survey has provided detailed information on 89 patients with symptomatic vitamin D deficiency under 5 years of age in hospitals in the current research group. The nationwide and second surveys estimated the overall annual incidence rate of symptomatic vitamin D deficiency in children under 5 years of age to be 3.5 (2.7-4.2) per 100,000 population. The second survey revealed 83% had bowed legs, 88% had exclusive breastfeeding, 49% had a restricted and/or unbalanced diet and 31% had insufficient sun exposure among the 89 patients. This is the first nationwide survey on definitive clinical vitamin D deficiency in children in Japan. Elucidating the frequency and characteristics of symptomatic vitamin D deficiency among children is useful to develop preventative public health strategies.

FGFR1 Analyses in Four Patients with Hypogonadotropic Hypogonadism with Split-Hand/Foot Malformation: Implications for the Promoter Region.

Heterozygous loss-of-function mutations of FGFR1 (fibroblast growth factor receptor 1) cause various disorders including hypogonadotropic hypogonadism with split-hand/foot malformation (HH-SHFM). We examined FGFR1 in four Japanese patients with HH-SHFM (cases 1-4) and the mother of case 4 with HH only. Cases 1 and 2 had heterozygous loss-of-function mutations with no dominant negative effect (c.289G>A, p.[G97S]; and c.2231G>C, p.[R744T]), and case 3 had a splice donor site mutation (c.1663+1G>T). Notably, case 4 had a maternally inherited 8,312 bp microdeletion that involved noncoding exon 1U and impaired FGFR1 expression. Furthermore, consistent with the presence of transcription-related histone marks (e.g., H3K4Me3, H3K4Me1, and H3K27Ac) and multiple transcription factor-binding sites around exon 1U, functional studies demonstrated a marked transactivation function of a 414-bp segment harboring the transcription start site. These results support the relevance of FGFR1 mutations to HH-SHFM, and argue for the presence of the FGFR1 core-promoter elements around exon 1U.

Use of liothyronine without levothyroxine in the treatment of mild consumptive hypothyroidism caused by hepatic hemangiomas.

There have been reports of the use of levothyroxine or levothyroxine plus liothyronine for consumptive hypothyroidism caused by hepatic hemangiomas. Administration of levothyroxine without liothyronine can be inadequate to maintain normal levels of both free T3 and free T4 in some patients. However, there is no report of treatment with liothyronine plus propranolol. We herein present a case in which we used liothyronine therapy for multifocal hepatic hemangiomas in a Japanese patient with low free T3 and normal free T4 levels. A 2-month-old Japanese male was referred to our hospital because of jaundice. Abdominal computed tomography showed multifocal hemangiomas in both lobes of the liver. TSH level was elevated, free T3 level was low, free T4 level was normal, and hypothyroidism due to hepatic hemangiomas was diagnosed. In addition to propranolol, liothyronine was started. We used liothyronine without levothyroxine for hypothyroidism because only free T3 level had decreased, whereas free T4 level remained in the normal range. The TSH and free T3 levels normalized in this patient in less than 1 month. The liothyronine dose was gradually reduced with regression of the hemangiomas, and liothyronine administration was discontinued at the age of 5 months. At the age of 11 months, growth and neurological development of the patient met age-specific norms, and he was euthyroid at that time. This is the first report demonstrating the use of liothyronine with propranolol for treatment of this type of consumptive hypothyroidism.

Hypertension is a characteristic complication of X-linked hypophosphatemia.

X-linked hypophosphatemia (XLH) is a group of rare disorders caused by defective proximal tubular reabsorption of phosphate. Mutations in the PHEX gene are responsible for the majority of cases. There are very few reports of long-term complications of XLH other than skeletal and dental diseases. The aim of this study was to identify the phenotypic presentation of XLH during adulthood including complications other than skeletal and dental diseases. The clinical and biochemical phenotype of 22 adult patients with a PHEX gene mutation were examined retrospectively from their medical records. 6 patients had hypertension. The average age of hypertension onset was 29.0 years. Secondary hyperparathyroidism preceded the development of hypertension in 5 patients. 1 patient developed tertiary hyperparathyroidism. 15 patients had nephrocalcinosis. 2 patients had chronic renal dysfunction. Patients with hypertension had a significantly lower eGFR (p=0.010) compared to patients without hypertension. No significant difference was found in any other parameters. To examine the genotype-phenotype correlation, 10 adult males were chosen for analysis. No significant genotype-phenotype correlation analysis was revealed in any of the complications. However, there was a possibility that the age at nephrocalcinosis onset was younger in the non-missense mutation group than in the missense mutation group (p=0.063). This study corroborated the view that early-onset hypertension could be one of the characteristic complications seen in XLH patients. Considering the limited number of our patients, further study is necessary to address a potential cause of hypertension. XLH patients require careful lifelong treatment.

Free T3 to free T4 ratio less than 2.0 suggests low T3 syndrome rather than central hypothyroidism from the age of two to eighteen years.

No serological cut-off exists to separate low T3 syndrome (LT) and central hypothyroidism (CH). The objective of this retrospective study was to propose such a cut-off. The first participant group comprised 52 patients from the age of six to twenty years. This group consisted of patients of 36 anorexia nervosa with LT and 16 CH. The second participant groups comprised 229 patients of all the same range of ages at the same hospital and included LT (n = 58) and CH (n = 4) patients, respectively. The third group of participants comprised 125 LT and 27 CH patients at the same hospital at all ages less than eighteen years. The last group of participants comprised 10 CH patients from the other two hospitals. The main outcome measure was fT3/fT4 ratio (pg/mL, ng/dL respectively). This ratio in the first group was significantly different (p < 0.05) between LT and CH. When the cut off value of fT3/fT4 was set as 2.0, the sensitivity of the LT and CH patients in the second group was 62% and 100%, respectively. This cut-off value of 2.0 was useful for distinguishing LT from CH only above the age of two years, as shown in the third group. The fT3/fT4 in 10 subjects with CH in the last group, aged 2 to 7 years, ranged from 2.55 to 7.71. In conclusion, fT3/fT4 less than 2.0 suggests LT rather than CH for patients from the age of two to eighteen years.