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Biomedical subjects

Peter A Lee

Publications and source records attributed to Peter A Lee.

10 recordsLinked to original sources
PubMed2003

The effects of manipulation of puberty on growth.

Short stature in adulthood can be considered as a disability because it can be associated with many difficulties including those of a psychological and social nature. Many factors can influence final adult height such as genetics, the magnitude of growth hormone (GH) secretion, height before puberty, and the onset and duration of puberty. A crucial factor affecting final adult height, however, is the total height achieved during puberty. The combination of GH and gonadotropin-releasing hormone analogues greatly enhances growth and their separate and combined use for the treatment of GH deficiency, central precocious puberty and other diagnoses in children and adolescents is discussed in this article.

Adolescent↗
PubMed2003

Age at menarche and racial comparisons in US girls.

BACKGROUND: Concern regarding change in the onset of sexual maturation of US girls has increased the need for current information on age at menarche from a national sample. Previous reports have been sparse and interpretation has been limited because of the racial composition and ages of the samples. OBJECTIVE: The objectives of this study were to estimate the distribution of age at menarche for all US girls and for non-Hispanic white, black, and Mexican American girls in the Third National Health and Nutrition Examination Survey and to test for racial differences. DESIGN: Menstrual status data were collected from 2510 girls aged 8.0 to 20.0 years. The Third National Health and Nutrition Examination Survey followed a complex, stratified, multistage probability cluster design. SUDAAN was used to calculate proportions of girls reaching menarche at an age. Ages at menarche were estimated by probit analysis at the ages at which 10%, 25%, 50%, 75%, and 90% of the girls attained menarche. RESULTS: Less than 10% of US girls start to menstruate before 11 years, and 90% of all US girls are menstruating by 13.75 years of age, with a median age of 12.43 years. This age at menarche is not significantly different (0.34 years earlier) than that reported for US girls in 1973. Age at menarche for non-Hispanic black girls was significantly earlier than that of white girls at 10%, 25%, and 50% of those who had attained menarche, whereas Mexican American girls were only significantly earlier than the white girls at 25%. CONCLUSION: Overall, US girls are not gaining reproductive potential earlier than in the past. The age at menarche of non-Hispanic black girls is significantly earlier than that of non-Hispanic white and Mexican American girls.

Adolescent↗
PubMed2003

International Small for Gestational Age Advisory Board consensus development conference statement: management of short children born small for gestational age, April 24-October 1, 2001.

OBJECTIVE: To provide pediatric endocrinologists, general pediatricians, neonatologists, and primary care physicians with recommendations for the management of short children born small for gestational age (SGA). METHODS: A 13-member independent panel of pediatric endocrinologists was convened to discuss relevant issues with respect to definition, diagnosis, and clinical management of short children born SGA. Panel members convened over a series of 3 meetings to thoroughly review, discuss, and come to consensus on the identification and treatment of short children who are born SGA. CONCLUSIONS: SGA is defined as birth weight and/or length at least 2 standard deviations (SDs) below the mean for gestational age ( 2 SD below the mean; this catch-up process is usually completed by the time they are 2 years of age. A child who is SGA and older than 3 years and has persistent short stature (ie, remaining at least 2 SD below the mean for chronologic age) is not likely to catch up and should be referred to a pediatrician who has expertise in endocrinology. Bone age is not a reliable predictor of height potential in children who are SGA. Nevertheless, a standard evaluation for short stature should be performed. A diagnosis of SGA does not exclude growth hormone (GH) deficiency, and GH assessment should be performed if there is clinical suspicion or biochemical evidence of GH deficiency. At baseline, insulin-like growth factor-I, insulin-like growth factor binding protein-3, fasting insulin, glucose, and lipid levels as well as blood pressure should be measured, and all aspects of SGA-not just stature-should be addressed with parents. The objectives of GH therapy in short children who are SGA are catch-up growth in early childhood, maintenance of normal growth in childhood, and achievement of normal adult height. GH therapy is effective and safe in short children who are born SGA and should be considered in those older than 2 to 3 years. There is long-term experience of improved growth using a dosage range from 0.24 to 0.48 mg/kg/wk. Higher GH doses (0.48 mg/kg/wk [0.2 IU/kg/d]) are more effective for the short term. Whether the higher GH dose is more efficacious than the lower dose in terms of adult height results is not yet known. Only adult height results of randomized dose-response studies will give a definite answer. Monitoring is necessary to ensure safety of medication. Children should be monitored for changes in glucose homeostasis, lipids, and blood pressure during therapy. The frequency and intensity of monitoring will vary depending on risk factors such as family history, obesity, and puberty.

Body Height↗
PubMed2002

The single testis: paternity after presentation as unilateral cryptorchidism.

PURPOSE: We determine if paternity is reduced among men with monorchidism (absent or removed testis) compared to men with unilateral cryptorchidism corrected during childhood by orchiopexy and controls. The group of men with an absent testis was determined among males presenting during childhood with only 1 descended testis. MATERIALS AND METHODS: Data were obtained by medical record review and a detailed questionnaire. Only men who had been successful at or attempted paternity for whom we had complete data were included in the study from the entire cohort of 584 men with former cryptorchidism, 23 with absent testis, 26 treated with orchiectomy and 706 controls. RESULTS: Percentages of men reporting success after attempting paternity did not differ among men with an absent testis (15 of 15, 100%), treated with orchiectomy (17 of 20, 85.0%), with corrected unilateral cryptorchidism (313 of 349, 89.7%) and controls (412 of 442, 93.2%). There was no difference for a subgroup of men with cryptorchidism judged to have an atrophic testis at orchiopexy (17 of 20, 85%) or those who underwent orchiectomy at initial attempted orchiopexy (8 of 10, 80%) and men who had subsequently undergone orchiopexy (9 of 10, 90.0%). Paternity was also not reduced in the group of men with only 1 testis (32 of 35, 91.4%) (monorchism plus orchiectomy) compared to either the corrected unilateral cryptorchid group or the control group. Of 637 testes 183 were recorded as impalpable on examination before surgery and 23 testes were absent, including 7 recorded as palpable. In fact, 12.1% (23 of 190) of testes that should have been recorded as impalpable were absent. CONCLUSIONS: This study failed to indicate that paternity is diminished among men with a single testis compared with the general population, regardless of the origin of the loss. About 12% of unilateral impalpable testes judged to be impalpable on examination before surgery were found to be absent after surgical exploration.

Adolescent↗
PubMed2002

National estimates of the timing of sexual maturation and racial differences among US children.

OBJECTIVE: To provide clinically meaningful, normative reference data that describe the timing of sexual maturity indicators among a national sample of US children and to determine the degree of racial/ethnic differences in these estimates for each maturity indicator. METHODS: Tanner staging assessment of sexual maturity indicators was recorded from 4263 non-Hispanic white, black, and Mexican American girls and boys aged 8.00 to 19.00 years as part of the Third National Health and Nutrition Examination Survey (NHANES III) conducted between 1988 and 1994. NHANES III followed a complex, stratified, multistage probability cluster design. SUDAAN was used to calculate the mean age and standard error for each maturity stage and the proportion of entry into a maturity stage and to incorporate the sampling weight and design effects of the NHANES III complex sampling design. Probit analysis and median age at entry into a maturity stage and its fiducial limits were calculated using SAS 8.2. RESULTS: Reference data for age at entry for maturity stages are presented in tabular and graphical format. Non-Hispanic black girls had an earlier sexual development for pubic hair and breast development either by median age at entry for a stage or for the mean age for a stage than Mexican American or non-Hispanic white girls. There were few to no significant differences between the Mexican American and non-Hispanic white girls. Non-Hispanic black boys also had earlier median and mean ages for sexual maturity stages than the non-Hispanic white and Mexican American boys. CONCLUSION: Non-Hispanic black girls and boys mature early, but US children completed their sexual development at approximately the same ages. The present reference data for the timing of sexual maturation are recommended for the interpretation of assessments of sexual maturity in US children.

Adolescent↗
PubMed2002

Delayed puberty.

Normal puberty is a time of life and a process of development that results in full adult maturity of growth, sexual development, and psychosocial achievement. Delayed puberty describes the clinical condition in which the pubertal events start late (usually > +2.5 SD later than the mean) or are attenuated in progression. The differential diagnosis includes syndromes of low gonadotropin production, usually constitutional delay of growth and maturation associated with chronic disease, but also an array of gene-mediated disorders, and syndromes of primary gonadal dysfunction with hypergonadotropic hypogonadism, including Turner and Klinefelter syndromes, and a group of acquired and genetic abnormalities. Diagnostic assessment and varied therapeutic modalities are discussed. The issues of androgen or estrogen therapy are important to assess, and growth hormone treatment remains a difficult dilemma.

Adolescent↗
PubMed2002

Genital size: a common adolescent male concern.

Long before adolescence, males hear insinuations about adequacy of penis size. This concern may heighten during teen years and persist to varying degrees into adulthood. Men tend to underestimate their own penis size. This chapter provides objective information about anatomy and growth of the penis, including data about normal sizes. Published data indicate that, although full growth may be reached at different ages during adolescence, size is similar for most adult males. Hopefully, this information will provide the basis for teenaged males to develop a healthy perspective and to avoid intimidation by unfounded claims about sexual enhancement or size enlargement techniques.

Adolescent↗
PubMed2002

Leydig cell function after cryptorchidism: evidence of the beneficial result of early surgery.

PURPOSE: We determined whether there are differences indicative of the function of the Leydig cell-pituitary axis in formerly unilateral cryptorchid men. Parameters were compared with those in control men. MATERIALS AND METHODS: We determined luteinizing hormone, testosterone, free testosterone, follicle-stimulating hormone, inhibin B, sperm density, motility and morphology, testicular volume, patient weight and age at orchiopexy or at other nonrelated childhood surgery in controls. RESULTS: Significant correlations were noted between hormone levels and other parameters. An inverse correlation between age of surgery and testosterone suggested the detrimental effect of deferring orchiopexy during childhood. Correlations of testosterone with sperm density, motility and morphology suggested a direct relationship between spermatogenesis and testosterone in cryptorchid men. An inverse relationship between body weight and testosterone was observed in each group. There was considerable variation in the range of parameters, sometimes extending into the abnormal range. However, results indicated no differences in mean free testosterone, testosterone or luteinizing hormone in the formerly cryptorchid and control groups, and no difference in time to conception in fertile, formerly cryptorchid men and controls. Furthermore, there were no differences in hormone levels in fertile (as indicated by paternity) and infertile formerly cryptorchid men. CONCLUSIONS: This study suggests that men who underwent orchiopexy in later childhood have subclinically decreased Leydig cell function. It may result in a less than optimal hormonal milieu for adult reproductive function. These data provide support for orchiopexy during infancy to preserve Leydig cell function and, thereby, potentially enhance fertility.

Adolescent↗
PubMedDate not supplied

Genital surgery among females with congenital adrenal hyperplasia: changes over the past five decades.

The treatment of intersex patients, including any patient born with genital ambiguity, is being reassessed. The re-evaluation is primarily focused upon the indications for and age of genital surgery, the impact of prenatal androgen levels upon gender development, and the potential for maximum sexual responsiveness as an adult. As a background to document changes in genital surgery for females with 21-hydroxylase congenital adrenal hyperplasia, this report is a review of surgical treatment of this most common form of genital ambiguity. Results document changes in the 1960s from clitorectomy to clitoroplasty using more refined techniques, but more interestingly a choice by parents against any surgery during childhood. This shift preceded the current impetus from intersex support groups. It appears to result from an appreciation by parents of variation in female genital configurations plus a realization that the clitoris will regress with the withdrawal of excessive androgens with relative size diminishing as growth proceeds. The primary impetus for this shift apparently has not been to preserve the vascular and neural supply to enhance sexual responsiveness, since parents in the past assumed that such could be preserved with appropriate surgical techniques.

Adrenal Hyperplasia, Congenital↗