Plasma 17-hydroxyprogesterone concentrations in ill newborn infants

International Newborn Screening Practices for the Early Detection of Congenital Adrenal Hyperplasia

INTRODUCTION

Newborn screening (NBS) programmes vary internationally in their approach to screening. Guidelines for congenital adrenal hyperplasia (CAH) screening recommend the use of two-tier testing and gestational age cutoffs to minimise false-positive results. The aims of this study were to describe (1) the approaches; (2) protocols used; and (3) available outcomes for CAH screening internationally.

METHODS

All members of the International Society for Neonatal Screening were asked to describe their CAH NBS protocols, with an emphasis on the use of second-tier testing, 17-hydroxyprogesterone (17OHP) cutoffs, and gestational age and birth weight adjustments. If available, screening outcomes were requested.

RESULTS

Representatives from 23 screening programmes provided data. Most (n = 14; 61%) recommend sampling at 48-72 h of life. Fourteen (61%) use single-tier testing and 9 have a two-tier testing protocol. Gestational age cutoffs are used in 10 programmes, birth weight cutoffs in 3, and a combination of both in 9. One programme does not use either method of adjusting 17OHP cutoffs. Case definition of a positive test and the response to a positive test differed between programmes.

CONCLUSIONS

We have demonstrated significant variation across all aspects of NBS for CAH, including timing, the use of single versus two-tier testing and cutoff interpretation. Collaboration between international screening programmes and implementation of new techniques to improve screen efficacy will facilitate ongoing expansion and quality improvement in CAH NBS.

Twenty Years of Neonatal Screening for Congenital Adrenal Hyperplasia in North-Eastern Italy: Role of Liquid Chromatography-Tandem Mass Spectrometry as a Second-Tier Test

BACKGROUND

Newborn screening for congenital adrenal hyperplasia (CAH) based on 17-hydroxyprogesterone (17-OHP) concentration in dried blood spots has been taking place in North-Eastern Italy since 2001. Since 2017, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been introduced, for the first time in Italy, as a second-tier test.

AIMS

Our study aims to evaluate, on the one hand, the effectiveness of the newborn screening for CAH after 20 years of testing and, on the other, the impact that the introduction of the second-tier test had on the diagnostic accuracy of the screening program.

METHODS

Since 2001 dried blood spots taken from newborns have been screened with a time-resolved fluoroimmunoassay for 17-OHP determination. Over the years, the cut-off levels of 17-OHP were adjusted according to gestational age. Since 2017, a second-tier test in LC-MS/MS was introduced for samples displaying fluoroimmunoassay 17-OHP exceeding the cut-off.

RESULTS

In total, 862,521 newborns have been screened over a period of 20 years. The total incidence of 21-hydroxylase deficiency (21-OHD) was 1:25,368, moreover, a case of 11-β-hydroxylase deficiency was identified. All these diagnoses were genetically confirmed. The sensitivity and specificity of the screening program were 97% and 99.4%, respectively. The use of LC-MS/MS as a second-tier test significantly reduced the recall rate and increased the positive predictive value.

CONCLUSIONS

Screening for CAH is useful in the neonatal diagnosis of a classic form of 21-OHD, allowing a precocious treatment of affected children. The introduction of an LC-MS/MS second-tier reduced the recall rate, avoiding unnecessary blood withdrawal and medical evaluations and preventing stress to families. Furthermore, it helped identify rarer forms of CAH.

Second-tier Testing for 21-Hydroxylase Deficiency in the Netherlands: A Newborn Screening Pilot Study

CONTEXT

Newborn screening (NBS) for classic congenital adrenal hyperplasia (CAH) consists of 17-hydroxyprogesterone (17-OHP) measurement with gestational age-adjusted cutoffs. A second heel puncture (HP) is performed in newborns with inconclusive results to reduce false positives.

OBJECTIVE

We assessed the accuracy and turnaround time of the current CAH NBS algorithm in comparison with alternative algorithms by performing a second-tier 21-deoxycortisol (21-DF) pilot study.

METHODS

Dried blood spots (DBS) of newborns with inconclusive and positive 17-OHP (immunoassay) first HP results were sent from regional NBS laboratories to the Amsterdam UMC Endocrine Laboratory. In 2017-2019, 21-DF concentrations were analyzed by LC-MS/MS in parallel with routine NBS. Diagnoses were confirmed by mutation analysis.

RESULTS

A total of 328 DBS were analyzed; 37 newborns had confirmed classic CAH, 33 were false-positive and 258 were categorized as negative in the second HP following the current algorithm. With second-tier testing, all 37 confirmed CAH had elevated 21-DF, while all 33 false positives and 253/258 second-HP negatives had undetectable 21-DF. The elevated 21-DF of the other 5 newborns may be NBS false negatives or second-tier false positives. Adding the second-tier results to inconclusive first HPs reduced the number of false positives to 11 and prevented all 286 second HPs. Adding the second tier to both positive and inconclusive first HPs eliminated all false positives but delayed referral for 31 CAH patients (1-4 days).

CONCLUSION

Application of the second-tier 21-DF measurement to inconclusive first HPs improved our CAH NBS by reducing false positives, abolishing the second HP, and thereby shortening referral time.

Newborn Screening for Congenital Adrenal Hyperplasia: Review of Factors Affecting Screening Accuracy

Newborn screening for 21-hydroxylase deficiency (21OHD), the most common form of congenital adrenal hyperplasia, has been performed routinely in the United States and other countries for over 20 years. Screening provides the opportunity for early detection and treatment of patients with 21OHD, preventing salt-wasting crisis during the first weeks of life. However, current first-tier screening methodologies lack specificity, leading to a large number of false positive cases, and adequate sensitivity to detect all cases of classic 21OHD that would benefit from treatment. This review summarizes the pathology of 21OHD and also the key stages of fetal hypothalamic-pituitary-adrenal axis development and adrenal steroidogenesis that contribute to limitations in screening accuracy. Factors leading to both false positive and false negative results are highlighted, along with specimen collection best practices used by laboratories in the United States and worldwide. This comprehensive review provides context and insight into the limitations of newborn screening for 21OHD for laboratorians, primary care physicians, and endocrinologists.

Congenital Adrenal Hyperplasia: Time to Replace 17OHP with 21-Deoxycortisol

Congenital adrenal hyperplasia (CAH) due to steroid 21-hydroxylase deficiency (21OHD) has a worldwide incidence of 1 in 15-20,000. Affected individuals have adrenal insufficiency and androgen excess; the androgen excess begins during fetal life, typically resulting in 46,XX disordered sexual development. In 21OHD, 17-hydroxyprogesterone (17OHP), the steroid proximal to 21-hydroxylase, accumulates. Most industrialized countries have newborn screening programs that measure 17OHP; such screening has permitted rapid detection of newborns with 21OHD, saving lives previously lost to mineralocorticoid deficiency and salt wasting. However, newborn screening is plagued by false positives. 17OHP is above most "cutoff values" in the first 24 h of life, is high in otherwise normal premature infants, and in many term infants with physiologic stress from unrelated diseases. In addition, newborn 17OHP may be elevated in other forms of CAH, including 11-hydroxylase deficiency, 3β-hydroxysteroid dehydrogenase deficiency, and P450 oxidoreductase deficiency. In 21OHD, some of the accumulated intra-adrenal 17OHP is converted to 21-deoxycortisol (21-deoxy) by 11β-hydroxylase (CYP11B1); 21-deoxy is not elevated in premature infants or in other forms of CAH, and hence is a more specific marker for 21OHD. However, 21-deoxy assays have not been generally available until recently, hence experience is limited. We urge clinical investigators, commercial reference laboratories, and newborn screening programs to investigate replacing 17OHP with 21-deoxy as the analyte of choice for studies of 21OHD.

The influence of seasonality and manufacturer kit lot changes on 17α-hydroxyprogesterone measurements and referral rates of congenital adrenal hyperplasia in newborns

Newborn screening for congenital adrenal hyperplasia (CAH) is performed by measuring the concentration of 17α-hydroxyprogesterone (17-OHP) in dried blood spots. Unfortunately, the level of 17-OHP varies due to multiple factors, and therefore, the false positive rate for the test is a challenge. We analyzed screening data from 2007 to 2015 to determine the effect of seasonal changes and manufacturer kit lot changes on 17-OHP values and on numbers of infants referred. Data from screening 2.2 million infants over a 9-year period indicates that in the NYS during the colder months, daily mean 17-OHP values are higher, more retests are performed, and more infants are referred even though fewer infants are born. The practice of using fixed cutoffs for referring infants for CAH leads to more false positive results in colder months. In addition, there was an overall 10% increase in the daily mean 17-OHP values from the 2 years before and after a manufacturer kit lot change that occurred in November 2013, suggestive of a functional change in the kit at that time.

CONCLUSION

Newborn screening programs should be cognizant of seasonal temperature variations and (un)anticipated manufacturer kit changes because they may affect 17-OHP values and CAH referral rates. What is Known: • Newborn screening for congenital adrenal hyperplasia is generally performed by measuring 17α-hydroxyprogesterone (17-OHP) levels in dried blood spots. • 17-OHP concentrations are affected by gestational age/weight of infant when specimen is collected, specimen collection time after birth, as well as race and sex of infant. What is New: • Seasonal temperature variations and unanticipated manufacturer kit changes affect 17-OHP levels and consequently referral rates in programs that use fixed cutoffs. • Daily mean 17-OHP is generally higher when the ambient temperature is lower.

Serum 17 alpha hydroxyprogesterone in normal full term and preterm vs sick preterm and full term newborns in a tertiary hospital

OBJECTIVES

To determine the variables affecting serum 17 hydroxyprogesterone (17OHP) in neonates born at a tertiary hospital in Mumbai, India.

METHODS

Serum 17OHP was measured in peripheral venous blood between 3rd to 5th day of life by competitive radioimmunoassay and on follow up at 3 mo of age. Serum 17OHP was compared among four groups [full term healthy(FT), full term stressed(FS), preterm healthy(PT), preterm stressed(PS)] by non-parametric tests (Kruskal Wallis (KW) test and Mann- Whitney (MW) test). Pearson's test was used to correlate natural log of serum 17OHP (ln17OHP) with variables like gestational age, birth weight, stress factor, sex, antenatal administration of glucocorticoids to mothers, Apgar score at 5 min and mode of delivery. Linear regression analysis was done using significant variables in Pearson's test to determine best predictors of ln17OHP.

RESULTS

The initial median (number of cases, inter-quartile range) serum 17OHP (ng/ml) for the four groups was as follows; FT 8.4 (33, 6-13); PT 20 (36, 11-29.5); FS 34 (29, 26-45) and PS 58 (24, 40.75-76.5) [total N = 122 newborns, p = 0.001]. Pearson's test showed that gestational age, birth weight, stress factor, Apgar score were negatively correlated with 17OHP whereas stress factor, mode of delivery, use of antenatal steroids in mothers were significantly positively correlated. However, stress factor emerged as the most important significant positive predictor (multiple R = 0.643, P = <0.0001). On follow up at 3 mo age, the median 17OHP (N = 73 newborns) had significantly decreased to normal level.

CONCLUSION

Stress due to neonatal illnesses like meconium aspiration, sepsis, birth asphyxia, etc. significantly elevate serum 17OHP and may lead to false positives in newborn screening for congenital adrenal hyperplasia.

Replication of clinical associations with 17-hydroxyprogesterone in preterm newborns

Nationally, newborn screening programs use 17-hydroxyprogesterone (17-OHP) as the biomarker to detect the rare but potentially fatal inherited disease, congenital adrenal hyperplasia. However, this biomarker is highly variable, with a high false-positive rate of detection, particularly in neonates born preterm. Several studies have examined various clinical and genetic factors to explain the variability of 17-OHP in preterm infants. The purpose of this study was to replicate previous clinical and genetic associations with 17-OHP in a well-characterized cohort of 762 preterm infants. We replicated previous findings that respiratory distress syndrome (p = 2 x 10(-3)) is associated with higher 17-OHP. Higher 17-OHP and false positives were significantly associated with lower gestational age and birth weight, as previously reported. Incorporating gestational age and birth weight together decreases the false-positive rate.

Effect of single and multiple courses of prenatal corticosteroids on 17-hydroxyprogesterone levels: implication for neonatal screening of congenital adrenal hyperplasia

Measurement of 17-hydroxyprogesterone (17-OHP) from filter-paper blood is widely used to screen for congenital adrenal hyperplasia (CAH). However, in pregnancies with an expected preterm delivery, prenatal treatment with steroids to induce pulmonary maturation could suppress the fetal adrenals and interfere with this screening. In 160 infants who were born between 25 and 35 wk of gestation, we measured 17-OHP in filter-paper blood at 72-96 h and compared the values between those who had not received antenatal steroids (n=50) and those who had (n=110). A single course of steroids was two 12-mg injections of betamethasone given within a 24-h interval: 30 infants received a half single course, 45 received a full single course, and 35 received multiple courses. Results are expressed as medians (25th percentile; 75th percentile). Blood 17-OHP differed significantly among groups: 23.7 (14.2; 30.7) nmol/L, 26.1 (15.0; 50.1) nmol/L, 20.1 (13.8; 29.1) nmol/L, and 14.9 (9.5; 26.2) nmol/L (for, respectively, no steroid, half a single course, a full single course, and multiple courses; p <0.05, multiple comparisons with the Kruskal-Wallis test). However, only infants who were treated with multiple antenatal courses of steroids had lower blood 17-OHP than those who were untreated (p <0.05 with the Mann-Whitney U test). In multiple regression analysis, steroid treatment and intrauterine growth retardation were significant negative predictors of blood 17-OHP, whereas respiratory distress syndrome was a significant positive predictor (multiple R=0.50, p <0.001). Multiple courses of steroids in preterm infants decrease 17-OHP values by approximately 30% in filter-paper blood, thus raising the risk of false-negative results in screening programs for CAH.

Development of the hypothalamic-pituitary-adrenal axis in the fetus and preterm infant

The development of the hypothalamic-pituitary-adrenal (HPA) axis in the human fetus is a complex process. The feto-placental unit may be responsible for important maturational processes in vital organ systems in the fetus. A late gestational cortisol surge may be important in fetal maturation, particularly maturation of the lungs. Several striking differences exist between the function of the HPA axis in the fetus and in adults, such as a relative deficiency of 3beta-hydroxysteroid dehydrogenase in the fetal adrenal cortex. With the transition from intrauterine to extra-uterine life several changes occur in the function of the HPA axis. In infants born before term, the function of the HPA axis may still be immature at both the central and adrenal level. This immaturity of the HPA axis may be important in the development of neonatal morbidity. The present review describes the development of the HPA axis in the fetus and in preterm infants and discusses the possible role of HPA immaturity in the development of neonatal morbidity.

Adrenal function in sick very preterm infants

Some very preterm neonates admitted to the neonatal intensive care unit show circulatory and respiratory problems that improve after administration of steroids. It is unclear whether these symptoms could be caused by adrenal insufficiency. The objective of our study was to investigate the cortisol levels and the cortisol release from the adrenals after ACTH in very preterm infants with and without severe illness and to find whether a relation exists between adrenal function and outcome. An ACTH test (0.5 microg) was performed on d 4 in 21 very preterm infants (gestational age, 25.6-29.6 wk; birth weight, 485-1265 g). Baseline cortisol and 17-hydroxyprogesterone (17OHP) levels and the cortisol levels 30, 60, and 120 min after ACTH administration were measured. The Score for Neonatal Acute Physiology was used to measure illness severity. All infants showed an increase in cortisol levels after ACTH, but the cortisol levels were significantly lower in the ventilated more severely ill infants. After adjusting for birth weight and gestational age, the mean baseline cortisol levels and cortisol/17OHP ratios were significantly lower and the 17OHP levels significantly higher in the ventilated infants compared with the nonventilated infants. Patients with an adverse outcome had significantly lower baseline cortisol/17OHP ratios and 60-min cortisol levels during ACTH testing (p = 0.002 and p = 0.03, respectively). These data suggest an insufficient adrenal response to stress in sick ventilated very preterm infants with gestational ages younger than 30 wk compared with nonventilated less sick preterm infants. Further studies are required to investigate whether supplementation with physiologic doses of hydrocortisone may benefit the outcome.

Influence of spironolactone on neonatal screening for congenital adrenal hyperplasia

AIM

To determine if the diuretic spironolactone cross reacts with 17alpha-hydroxyprogesterone (17OHP) in an enzyme linked immunosorbent assay (ELISA) kit used for the mass screening of congenital adrenal hyperplasia.

METHODS

Concentrations of 17OHP on a blood filter paper disc were measured using an ELISA kit (kit C-7: ENZAPLATE N-17alpha -OHP-7; Chiron, Tokyo, Japan). The cross reactivity of spironolactone and its metabolites with 17OHP was determined. The concentrations of spironolactone and its metabolites in blood were measured using HPLC (high performance liquid chromatography).

RESULTS

Spironolactone cross reacted with 17OHP using kit C-7 (0.01%), by increasing 17OHP concentration in a dose dependent manner. The blood concentration of spironolactone and its metabolites was nearly 900 ng/ml, high enough to show an additive effect on the 17OHP concentration. About 12% of the false positive cases screened using the kit were due to the administration of spironolactone.

CONCLUSIONS

Spironolactone interferes with 17OHP concentrations, leading to false positive test results for CAH.

[Neonatal screening of congenital adrenal hyperplasia due to 21-hydroxylase deficiency: Lille experience 1980-1996]

AIM

The results of the neonatal screening of congenital adrenal hyperplasia due to 21-hydroxylase deficiency by 17-hydroxyprogesterone measurement from blood spot on blotting-paper in 408,138 newborns in the French Nord-Pas-de-Calais region from 1980 to 1996 are reported.

METHODS

This measurement successively used a tracer tritium labelled (RIA H3), 125 iodine (RIA I125), then immunofluorometric method (Delfia). From 1992, sampling was systematically performed at the third day of life.

RESULTS

Thirty-three cases were detected and confirmed (20 boys and 13 girls). Diagnosis was made before recalling on a clinical basis in three boys and eight girls. In 22 cases (17 boys and five girls) when diagnosis was not made before recalling, it could have been suspected in three girls because of a sex ambiguity once associated with dehydration and in eight boys because of failure to thrive (six times) or a marked dehydration (twice). Lack of sex ambiguity in two girls characterized non classical form of the illness. These two patients benefited from the early detection of the illness on growth data. Out of 49 subjects who died before recall, three could be suspected of bearing 21-hydroxylase deficiency. One single false negative case was found, which led to decrease cut-off value. On the other hand, false positive cases were frequent (0.37%), mainly in premature newborns (88% of cases).

CONCLUSION

Although decrease of median age for recall at 7 days did not prevent the occurrence of two cases of dehydration, neonatal screening of 21-hydroxylase deficiency appears to be efficient, as far as diagnostic strategy is considered.

Immature adrenal steroidogenesis in preterm infants

Screening for congenital adrenal hyperplasia is associated with a high rate of false positive results in preterm infants. Some RIA studies have detected elevated levels of 17 alpha-hydroxy-progesterone in severely ill preterm infants. However, because the antisera used with RIAs have a high degree of cross-reactivity, RIA results may not be reliable. Adrenal steroidogenesis was evaluated in 33 preterm infants born at less than 32 weeks' gestation using reversed-phase high performance liquid chromatography. 17 alpha-hydroxyprogesterone, 11-deoxycortisol, and/or corticosterone were detectable temporarily at about 29 weeks of equivalent gestational age in 27 of 33 preterm infants. Levels of cortisol and cortisone were markedly decreased in 4 of 16 infants whose mothers had received steroids. These findings suggest that the activities of 21-hydroxylase, 11 beta-hydroxylase, and 18-hydroxylase are decreased at about 29 weeks of equivalent gestational age. Steroid levels should be carefully monitored in preterm infants with elevated intermediate steroids and preterm infants whose mothers receive steroids before delivery using reversed-phase high performance liquid chromatography.

Serum 17 alpha-hydroxyprogesterone in infants and children as measured by a direct radioimmunoassay kit

A direct 17 alpha-hydroxyprogesterone (17-OHP) radioimmunoassay kit was used for the assay of samples from 219 infants and children. The kit was used according to the manufacturer's protocol on unextracted serum or plasma and also on reconstituted material extracted from the serum with propanol-heptane. The extraction protocol recovers approximately 88% of 17-OHP. Patients were grouped as infants 3-90 days (96 subjects) or older children, adolescents and young adults 91 days-20 years (123 subjects). 17-OHP results by the direct and extraction protocols correlated but the slopes of the regression lines (0.43 and 0.63) differed in the two groups, indicating that only about 49% of the immunoreactive material measured by the kit in the infants was 17-OHP whereas the corresponding percentage was 72% in the older children. Despite this nonspecificity, the present antibody is much more specific for 17-OHP in the presence of neonatal plasma steroids than that used previously. Reference values were obtained for the two groups using the method with and without an extraction step. 17-OHP values on four untreated patients with CAH were clearly elevated at the time of diagnosis. It is recommended that when the kit is used with neonatal and infant samples, an extraction step should be incorporated to enhance specificity.

Virilisation of female preterm infants

Two cases of hypertrophy of the clitoris in premature girls are reported; this was associated with persistently high concentrations of adrenal fetal zone androgens.

Congenital adrenal hyperplasia

An autosomal recessive disorder, congenital adrenal hyperplasia, results from a deficiency in the activity of one of the five enzymes required for cortisol biosynthesis. More than 90% of cases are related to deficiency in 21-hydroxylase enzyme activity, which is required for the conversion of 17OH-progesterone to 11-deoxycortisol. Treatment of congenital adrenal hyperplasia consists of steroid replacement to ensure normal growth and reproductive potential.

Value of selective screening for congenital adrenal hyperplasia in Hungary

Measurement of the 17-hydroxyprogesterone concentration in blood spots was used to identify cases of congenital adrenal hyperplasia among patients with inappropriate virilisation, or salt wasting, or both. Between 1978 and 1986 61 were identified among 707 patients (278 neonates, 204 infants, and 225 children). The incidence of classic congenital adrenal hyperplasia was calculated for a seven year prospective trial period using the blood spot 17-hydroxyprogesterone method in selective screening. There were 38 salt losers and 14 simple virilisers in 968,303 live births, an incidence of congenital adrenal hyperplasia of 1:18,000 in the Hungarian population. Selective screening led to earlier diagnosis of congenital adrenal hyperplasia and a pronounced decrease in mortality. A central laboratory to measure the blood spot 17-hydroxyprogesterone concentrations is valuable for the investigation of patients at risk for congenital adrenal hyperplasia in countries where blood steroid assays are not readily available.

Postnatal course of plasma levels of adrenocortical steroids in premature infants with and without NaCl supplementation

To assess the adrenocortical response of premature infants to alterations in sodium balance, the postnatal course of plasma progesterone, 11-deoxycorticosterone, corticosteronoe, aldosterone, 17-hydroxyprogesterone, 11-deoxycortisol, cortisol and cortisone was compared in healthy premature infants kept on low (1-2 mEq/kg per day) or high (3-5 mEq/kg per day) sodium diet. The mean birthweight (1470 g, range: 1210-1670 g vs 1410 g, range: 1130-1750 g) and mean gestational age (30.5 weeks, range: 29-32 weeks vs 30.2 weeks, range: 28-32 weeks) in the low and high sodium groups, respectively, were similar. Simultaneous steroid hormone measurements were made weekly up to the 5th week of life using mechanized Sephadex LH-20 multicolumn chromatography and standardized radioimmunoassays. It was demonstrated that in response to renal salt wasting and negative sodium balance there was a significant rise in plasma aldosterone concentration. The plasma levels of other individual corticosteroids generally declined with advancing age, the initial fall, however, was followed by a transient and insignificant but simultaneous increase in 11-deoxycortisol, cortisol, cortisone and corticosterone in prematures on low a sodium diet. This effect could be prevented by giving NaCl supplement. The NaCl-suppressible increase in adrenocortical activity may be the result of the combined effect of stress or angiotensin 11-induced adrenocorticotropic hormone (ACTH) release and/or prolactin-mediated enhanced adrenal response to ACTH.

Blood spot glucocorticoid concentrations in ill preterm infants

The adrenocortical response to stress was studied longitudinally in 10 ill preterm infants using measurements of cortisol and 170H-progesterone concentrations in filter paper blood spots. Mean cortisol and 170H-progesterone concentrations reached a peak of 2200 nmol/l and 65 nmol/l, respectively, between the third and fifth days of life. These concentrations far exceeded those observed in older children and adults subjected to stress as a result of surgery. Further pulses of endogenous cortisol production of 4000 nmol/l or more occurred in association with clinical complications such as intraventricular haemorrhage. These results indicate that infants undergoing intensive care are unduly stressed. Consideration should be given to providing enough sedation and appropriate analgesia for ill preterm infants during painful procedures such as insertion of venous cannulae and arterial puncture.

Radioimmunoassay of blood-spot 17 alpha-hydroxyprogesterone in the management of congenital adrenal hyperplasia

A robust assay for routine measurement of blood-spot 17 alpha-hydroxyprogesterone (17-OHP) concentrations has been developed using a magnetizable, solid-phase antiserum and an 125I-radioligand. The working range of this assay (13.5-500 nmol/L) is well suited for the initial diagnosis of congenital adrenal hyperplasia (CAH) and for monitoring replacement therapy in CAH patients. Data derived from multiple blood-spot samples, collected on two consecutive days, provide 17-OHP profiles. These profiles have been used to construct a chart allowing a rapid visual assessment of the efficacy of replacement therapy in CAH patients. Measurement of 17-OHP in the blood-spots of overtreated patients and accurate determination of normal range values in healthy infants relied on development of a sensitive assay (range 1.7-34 nmol/L). In the blood-spots of normal male (n = 50) and female (n = 50) infants collected 5-7 days after birth, 17-OHP concentrations were 7.62 +/- 2.55 nmol/L and 7.32 +/- 2.87 nmol/L respectively. Retrospective measurement of this steroid in samples from known CAH patients (n = 4), which had values ranging from 224 to 2145 nmol/L, support a role for measurement of blood-spot 17-OHP in high-risk screening programmes.

The interpretation of bloodspot 17 alpha-hydroxyprogesterone levels in term and pre-term neonates

Bloodspot 17 alpha-hydroxyprogesterone, plasma cortisol, plasma sodium and urinary 17 alpha-hydroxyprogesterone, cortisol, sodium and creatinine levels were determined in 24 term and 32 pre-term infants on the third, eighth and fourteenth days of life. Pre-term infants, whether 'well' or 'sick', had significantly raised bloodspot 17 alpha-hydroxyprogesterone levels (up to 158 nmol/L) compared with those found in term infants (up to 18.8 nmol/L). Urinary 17 alpha-hydroxyprogesterone creatinine ratios were also higher in pre-term infants. Plasma cortisol results showed similar ranges for term and pre-term infants, and bloodspot 17 alpha-hydroxyprogesterone/plasma cortisol ratios for day 3 specimens correlated with the degree of prematurity. These results may be due either to immature enzyme systems in the pre-term baby or to an excess of related steroids cross-reacting in the 17 alpha-hydroxyprogesterone assay. We propose the use of two distinct upper limits of normal of 20 nmol/L (term infants) and 200 nmol/L (pre-term infants), for the interpretation of bloodspot 17 alpha-hydroxyprogesterone levels at the end of the first week of life.

Response to ACTH in the newborn

Adrenocortical function was studied in 52 newborn infants who had been divided into three groups: preterm well, preterm ill, and term ill. Basal plasma 17-hydroxyprogesterone concentrations were significantly increased in both groups of preterm infants. There was no significant difference in basal plasma cortisol concentrations, although they were highest in preterm ill infants. All infants responded to adrenocorticotrophic hormone (ACTH) stimulation (36 micrograms/kg intramuscularly) with a two to three fold increase in the concentration of both steroids. The peak plasma 17-hydroxyprogesterone response was significantly higher in preterm ill infants. A subgroup of five infants, who were highly stressed but had undetectable basal plasma cortisol concentrations, also showed an appropriate response to ACTH. The results provide useful reference data to assess adrenal function in the infant of a mother given glucocorticoids during pregnancy. There is also a change from the pattern of fetal adrenal steroidogenesis soon after birth, which may be affected by exogenous ACTH stimulation. Roughly 10% of stressed newborns failed to synthesise cortisol basally; temporary glucocorticoid replacement for such infants may be appropriate.

Biochemical aspects of congenital adrenal hyperplasia

The assay of 17 alpha-hydroxyprogesterone in blood spots on filter paper forms the basis of neonatal screening programmes to detect congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. The blood concentrations of this hormone in the neonate varies with gestation age (term v preterm), age after birth, time of day and illness. Broad reference ranges for blood spot 17 alpha-hydroxyprogesterone concentrations are therefore quoted for healthy term infants and these ranges are not appropriate for the interpretation of values in preterm and sick newborns. There is a risk of a false-negative or of a false-positive diagnosis. Many of the above difficulties may result from variations in assay performance due to changes in the pattern of steroids produced by the adrenal gland which in turn relate to morphological changes in the adrenal cortex at this age. The purpose of this presentation is to define the complex steroid milieu of the newborn human and briefly to review the factors which determine the function of the adrenal gland, since these influence the extent to which an assay for this steroid needs to be evaluated before application to neonatal screening for CAH. The data to be presented derive from the capillary column gas chromatographic analysis (GC) of steroids in urine since this provides the best method to display the overall steroid production of the organism. The GC method has itself been refined so that CAH can now be reliably diagnosed using this method, but the information from this work will also be judged for its relevance to the problems encountered in the neonatal screening for CAH by blood spot analysis.

Clinical aspects of congenital adrenal hyperplasia: early diagnosis and prognosis

The neonatal presentation of congenital adrenal hyperplasia is either virilization of females or salt loss in both sexes. Early diagnosis is based on the rapid measurement of plasma 17 alpha-hydroxyprogesterone. Milder forms of congenital adrenal hyperplasia can present later in life with abnormalities of somatic or sexual development. The majority of cases of congenital adrenal hyperplasia are clinically diagnosable in the first 2-3 weeks of life: the need for screening for the remaining missed cases and the late onset types remains to be established.

Diurnal variation in blood 17-hydroxyprogesterone concentrations in untreated congenital adrenal hyperplasia

Blood spot 17-hydroxyprogesterone concentrations were measured serially over 24 hours in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency before they started treatment with glucocorticoids, and the development of diurnal rhythm in pituitary-adrenal activity was studied. Five infants aged 2 to 26 days showed an intradiem variation of 17-hydroxyprogesterone concentrations within the diagnostic range but without a characteristic diurnal pattern. Blood spot 17-hydroxyprogesterone values in a further eight patients aged 3 months to 6.5 years showed a diurnal rhythm, with high concentrations in the morning and a nadir in the evening. The results suggest that a diurnal rhythm in pituitary-adrenal activity may develop as early as the third month of life in those infants with an increased endogenous concentration of adrenocorticotrophic hormone.

Bloodspot 17 alpha-hydroxyprogesterone radioimmunoassay for diagnosis of congenital adrenal hyperplasia and home monitoring of corticosteroid replacement therapy

A convenient and inexpensive radioimmunoassay for bloodspot 17 alpha-hydroxyprogesterone (17-OHP) has been evaluated in the screening of newborn infants for congenital adrenal hyperplasia (CAH) and for home monitoring of CAH patients on steroid replacement therapy. In the screening study, analysis of 491 bloodspots taken for routine screening programmes for phenylketonuria and hypothyroidism established the upper limit of normal for infants aged 5-10 days as 64 nmol 17-OHP/l blood (99.9 centile). Home monitoring of patients by examination of fingerprick bloodspot 17-OHP profiles taken by parents over Saturday and Sunday on consecutive weekends showed that changes in control occurred as a result of transition from inpatient to outpatient treatment or following adjustment of steroid replacement regimens. The method was found to be valuable in the diagnosis and management of children with CAH.