Aldosterone excretion in normal children and in children with adrenal hyperplasia

The Search for the Causes of Common Hyperandrogenism, 1965 to Circa 2015

From 1965 to 2015, immense strides were made into understanding the mechanisms underlying the common androgen excess disorders, premature adrenarche and polycystic ovary syndrome (PCOS). The author reviews the critical discoveries of this era from his perspective investigating these disorders, commencing with his early discoveries of the unique pattern of plasma androgens in premature adrenarche and the elevation of an index of the plasma free testosterone concentration in most hirsute women. The molecular genetic basis, though not the developmental biologic basis, for adrenarche is now known and 11-oxytestosterones shown to be major bioactive adrenal androgens. The evolution of the lines of research into the pathogenesis of PCOS is historically traced: research milestones are cited in the areas of neuroendocrinology, insulin resistance, hyperinsulinism, type 2 diabetes mellitus, folliculogenesis, androgen secretion, obesity, phenotyping, prenatal androgenization, epigenetics, and complex genetics. Large-scale genome-wide association studies led to the 2014 discovery of an unsuspected steroidogenic regulator DENND1A (differentially expressed in normal and neoplastic development). The splice variant DENND1A.V2 is constitutively overexpressed in PCOS theca cells in long-term culture and accounts for their PCOS-like phenotype. The genetics are complex, however: DENND1A intronic variant copy number is related to phenotype severity, and recent data indicate that rare variants in a DENND1A regulatory network and other genes are related to PCOS. Obesity exacerbates PCOS manifestations via insulin resistance and proinflammatory cytokine excess; excess adipose tissue also forms testosterone. Polycystic ovaries in 40 percent of apparently normal women lie on the PCOS functional spectrum. Much remains to be learned.

Adrenal disease in pregnancy

Adrenal disorders in pregnancy are relatively rare, yet can lead to significant maternal and fetal morbidity. Making a diagnosis is challenging as pregnancy may alter the manifestation of disease, many signs and symptoms associated with pregnancy are also seen in adrenal disease, and the fetal-placental unit alters the maternal endocrine metabolism and hormonal feedback mechanisms. The most common cause of Cushing's syndrome in pregnancy is an adrenal adenoma, followed by pituitary etiology, adrenal carcinoma, and other exceedingly rare causes. Medical therapy of Cushing's syndrome includes metyrapone and ketoconazole, but generally surgical treatment is more effective. Exogenous corticosteroid administration is the most common cause of adrenal insufficiency, followed by the endogenous causes of ACTH or CRH secretion. Primary adrenal insufficiency is least common. A low early morning cortisol <3 mcg/dL (83 mmol/L) in the non-stressed state and in the setting of typical clinical symptoms confirms the diagnosis. In the second and third trimester cortisol rises to levels 2-3 fold above those in the non-pregnant state, therefore a baseline level of <30 mcg/dL (823 mmol/L) warrants further evaluation. ACTH stimulated normal cortisol values have been established for each trimester. Hydrocortisone, which does not cross the placenta, is the glucocorticoid treatment of choice, and fludrocortisone is used as mineralocorticoid replacement in patients with primary disease. Congenital adrenal hyperplasia is an autosomal recessive disorder; 21-hydroxylase deficiency (21OHD) is the most common form of the disease. Non-classical 21OHD is most common, followed by the salt-wasting and simple virilizing forms. The treatment of choice for pregnant women affected with CAH is hydrocortisone, and fludrocortisones is added for those with the salt-wasting form of the disease. If the fetus is at risk for classical CAH, dexamethasone treatment can be used prenatally to prevent masculinization of the genitalia in a female infant. Because dexamethasone crosses the placenta, it should not be used to treat pregnant women with CAH if the fetus is not at risk for the disease.

Aldosterone-to-renin ratio as a marker for disease severity in 21-hydroxylase deficiency congenital adrenal hyperplasia

CONTEXT

Congenital adrenal hyperplasia (CAH) owing to 21-hydroxylase deficiency (21 OHD) is classified clinically in decreasing order of severity into salt-wasting, simple-virilizing, and nonclassical forms. Causative mutations in the CYP21A2 gene dictate the degrees of adrenal enzyme defect. Salt-wasting crises due to aldosterone deficiency are clinically apparent in the salt-wasting form but not in other forms of 21 OHD.

OBJECTIVES

This study examined the ratio of serum aldosterone to plasma renin activity as an index of sodium wasting in patients with 21 OHD CAH, heterozygotes, and normal individuals.

DESIGN

This was a cross-sectional, retrospective, noninterventional study.

PATIENTS AND OTHER PARTICIPANTS

A total of 402 individuals were included: 224 patients affected with 21 OHD CAH and 178 unaffected subjects. Classification into each diagnostic group was made primarily on the basis of clinical and hormonal features. Affected or unaffected status was confirmed by genotype of CYP21A2. All subjects were on ad lib diets without restrictions. Salt-wasting status was examined by sodium deprivation testing in 32 salt-wasting subjects and 14 simple virilizing subjects.

RESULTS

The ratio of serum aldosterone to plasma renin activity was found to discriminate well between the different groups of disease severity. The lowest ratios, indicative of the least sodium conservation, were seen in the salt-wasting group with increasing ratios in the simple virilizing, nonclassical, and unaffected groups. This ratio remained stable with age.

CONCLUSION

The ratio of serum aldosterone to plasma renin activity provides a simple index to compare groups of patients with varying degrees of 21 OHD.

The natural history and genotype-phenotype nonconcordance of HLA identical siblings with the same mutations of the 21-hydroxylase gene

The correlation of genotype to phenotype in congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency has been investigated thoroughly since the mapping of the CYP21 gene to the short arm of chromosome 6. In most instances, it is possible to accurately predict the phenotype based on genoytpe; however, in a small number of patients, individuals with identical mutations demonstrate variable phenotypes. We report two HLA-identical brothers who represent a striking case of genotype-phenotype nonconcordance in CAH. Molecular genetic analysis showed both patients had mutations in intron 2 and exon 10 of CYP21. Both brothers underwent salt-deprivation tests at similar ages over three separate hospital admissions. Patient 1 was diagnosed with simple virilizing CAH and was able to maintain sodium balance during salt deprivation tests. Patient 2, 3 years younger, was diagnosed with salt-wasting CAH and was unable to maintain sodium balance but progressively increased his aldosterone secretion with age.

Steroid disorders in children: congenital adrenal hyperplasia and apparent mineralocorticoid excess

Our research team and laboratories have concentrated on two inherited endocrine disorders, congenital adrenal hyperplasia (CAH) and apparent mineralocorticoid excess, in thier investigations of the pathophysiology of adrenal steroid hormone disorders in children. CAH refers to a family of inherited disorders in which defects occur in one of the enzymatic steps required to synthesize cortisol from cholesterol in the adrenal gland. Because of the impaired cortisol secretion, adrenocorticotropic hormone levels rise due to impairment of a negative feedback system, which results in hyperplasia of the adrenal cortex. The majority of cases is due to 21-hydroxylase deficiency (21-OHD). Owing to the blocked enzymatic step, cortisol precursors accumulate in excess and are converted to potent androgens, which are secreted and cause in utero virilization of the affected female fetus genitalia in the classical form of CAH. A mild form of the 21-OHD, termed nonclassical 21-OHD, is the most common autosomal recessive disorder in humans, and occurs in 1/27 Ashkenazic Jews. Mutations in the CYP21 gene have been identified that cause both classical and nonclassical CAH. Apparent mineralocorticoid excess is a potentially fatal genetic disorder causing severe juvenile hypertension, pre- and postnatal growth failure, and low to undetectable levels of potassium, renin, and aldosterone. It is caused by autosomal recessive mutations in the HSD11B2 gene, which result in a deficiency of 11beta-hydroxysteroid dehydrogenase type 2. In 1998, we reported a mild form of this disease, which may represent an important cause of low-renin hypertension.

Disease expression and molecular genotype in congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Genotyping for 10 mutations in the CYP21 gene was performed in 88 families with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Southern blot analysis was used to detect CYP21 deletions or large gene conversions, and allele-specific hybridizations were performed with DNA amplified by the polymerase chain reaction to detect smaller mutations. Mutations were detected on 95% of chromosomes examined. The most common mutations were an A----G change in the second intron affecting pre-mRNA splicing (26%), large deletions (21%), Ile-172----Asn (16%), and Val-281----Leu (11%). Patients were classified into three mutation groups based on degree of predicted enzymatic compromise. Mutation groups were correlated with clinical diagnosis and specific measures of in vivo 21-hydroxylase activity, such as 17-hydroxyprogesterone, aldosterone, and sodium balance. Mutation group A (no enzymatic activity) consisted principally of salt-wasting (severely affected) patients, group B (2% activity) of simple virilizing patients, and group C (10-20% activity) of nonclassic (mildly affected) patients, but each group contained patients with phenotypes either more or less severe than predicted. These data suggest that most but not all of the phenotypic variability in 21-hydroxylase deficiency results from allelic variation in CYP21. Accurate prenatal diagnosis should be possible in most cases using the described strategy.

Aldosterone synthesis in salt-wasting congenital adrenal hyperplasia with complete absence of adrenal 21-hydroxylase

BACKGROUND

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is a disorder of cortisol and aldosterone biosynthesis that results from mutations in the CYP21 gene encoding the adrenal 21-hydroxylase P-450c21. It can cause severe salt wasting in newborns that requires long-term treatment with glucocorticoids and mineralocorticoids. We describe a spontaneous partial recovery from this disorder in a 19-year-old woman who had discontinued treatment.

METHODS

We measured plasma and urinary levels of adrenal hormones, plasma renin activity, and sodium balance longitudinally in the patient and four other patients in whom adrenal hyperplasia had been diagnosed in infancy and in whom DNA analysis had predicted a complete absence of functional P-450c21. The ratio of plasma renin activity to urinary aldosterone was used as a measure of the response of the adrenal zona glomerulosa. Two patients underwent intravenous infusion of [3H]progesterone for the measurement of extraadrenal production of 21-hydroxylated precursors of aldosterone.

RESULTS

The patient who had discontinued her medication excreted a normal amount of aldosterone (20.0 nmol per square meter of body-surface area per day) while following a diet low in sodium. Her ratio of plasma renin activity to urinary aldosterone-18-glucuronide excretion was 1.7 after three days of sodium restriction, as compared with a ratio of 4.7 at the age of nine years (normal range, 0.03 to 0.1). The percentage of extraadrenal conversion of progesterone to deoxycorticosterone was low. The four other patients had variable responses to sodium restriction after the neonatal period (range for plasma renin activity:urinary aldosterone-18-glucuronide, 1.9 to 19.4).

CONCLUSIONS

Although patients with salt-wasting 21-hydroxylase deficiency have functionally equivalent mutations in their CYP21 genes, they may vary from one another and over time in their ability to produce mineralocorticoids. This variation may be attributable to another adrenal enzyme with 21-hydroxylase activity.

Ontogeny of aldosterone glucuronidation by the human newborn

We studied urine excretion of free aldosterone and aldosterone-18-glucuronide by well preterm and fullterm infants during the first week after birth. Total urine aldosterone excretion (UAE) was not influenced by gestational age, but preterm infants excreted a lower percentage of total aldosterone as glucuronide. Mean +/- 2%, 74 +/- 2% and 77 +/- 3% on Day 1 (P less than 0.01); 88 +/- 2%, 74 +/- 2% and 72 +/- 3% on Day 4 (P less than 0.01); and 86 +/- 4%, 76 +/- 3% and 72 +/- 4% on Day 7 (P less than 0.10). Total UAE increased from Day 1 to Day 7 for infants less than 33 wk (P less than 0.05), but not for more mature infants. Percentage excreted as conjugate did not alter during the first week for any group. For infants less than 33 wk, total UAE by those who received prenatal glucocorticoids was higher than by those who did not on Day 1 (0.96 +/- 0.15 vs 0.45 +/- 0.15 nmol/kg per day; P less than 0.025). Percentage excreted as conjugate was not influenced by prenatal glucocorticoids at any postnatal age. Sodium balance was positive for all groups by 1 wk, and did not correlate with either free, conjugated or total UAE for any of the groups in this study. These data suggest that the ability to conjugate aldosterone is related to gestational maturity, and is not altered by prenatal glucocorticoids in infants less than 33 wk gestation. This aspect of aldosterone metabolism does not appear to relate to early postnatal sodium balance.

Determination of aldosterone secretion rate utilizing mixed mode and high performance liquid chromatography

A simpler method for determining aldosterone secretion rate (ASR) has several applications. High performance liquid chromatography (HPLC) has several advantages over traditional chromatographic methods for purification to constant specific activity of aldosterone liberated from its 18-glucuronide by acid hydrolysis. We found it necessary to introduce several modifications to remove urochromes before HPLC. Two methods for determining ASR were developed. With Method A a more traditional initial procedure was followed, and Sephadex LH-20 chromatography allowed removal of considerable urochromes before HPLC. However, aldosterone recovery was improved with Method B, which employed several bonded phase silica derivatives (Sepralytes) and a PBE 94 column to remove urochromes before HPLC. With this procedure the Sephadex LH-20 chromatography was not required. Aldosterone purification to constant specific activity was achieved by HPLC on a diol column with a normal phase system, and quantification was performed by RIA. ASR determinations were equivalent with both methods. This methodology should be applicable to other steroid secretory rate determinations and to applications involving purification of steroid conjugates.

Is salt-wasting in congenital adrenal hyperplasia due to the same gene as the fasciculata defect?

Clinical studies in patients with 21-hydroxylase deficiency congenital adrenal hyperplasia (CAH) were designed to ascertain the genetics of the salt-wasting component of the disorder. The gene controlling aldosterone biosynthesis may not be the same gene that controls 21-hydroxylase in the adrenal zona fasciculata. This we infer from the following clinical observations: (1) concordance for salt-wasting is not observed in all HLA-identical sibs with CAH; (2) the defect in aldosterone biosynthesis does not persist throughout life as does the fasciculata defect; (3) there is a significantly increased gene frequency of B40 and Bw47 in salt-wasting CAH; (4) obligate heterozygote parents of patients with salt-wasting CAH do not express a partial defect in aldosterone biosynthesis, as they do in the fasciculata. These observations cast doubt on the accepted concept of the autosomal recessive transmission of the glomerulosa 21-hydroxylase deficiency.

Male pseudohermaphroditism due to multiple defects in steroid-biosynthetic microsomal mixed-function oxidases. A new variant of congenital adrenal hyperplasia

A six-month-old 46,XY infant with a female phenotype and ambiguous genitalia was evaluated for male pseudohermaphroditism. The principal findings were (1) low basal plasma levels of all measured C19 steroids and their sulfates, which were unchanged or only minimally increased after stimulation with human chorionic gonadotropin or ACTH, (2) no urinary metabolites of C19 11-deoxy steroids, and decreased amounts of C19 11-oxosteroids, (3) normal basal plasma cortisol levels and normal urinary excretion of cortisol metabolites, (4) high plasma corticosterone and deoxycorticosterone levels and elevated urinary excretion of their metabolites, (5) high plasma progesterone and pregnenolone levels and increased urinary excretion of pregnanediol and pregnenediol, (6) high plasma 17 alpha-hydroxyprogesterone and 21-deoxycortisol levels and increased urinary excretion of pregnanetriol, 17 alpha-hydroxypregnanolone, and pregnenetriolone, (7) high plasma and urinary levels of 5-pregnene-3 beta,20 alpha-diol sulfate, (8) low plasma levels of 21-hydroxy-pregnenolone and 5-pregnene-3 beta,17 alpha, 20 alpha-triol sulfate, (9) high plasma ACTH levels, and (10) suppression of the high plasma steroid levels by dexamethasone. The unusual pattern of plasma and urinary steroids indicated that this child had multiple abnormalities of steroid-biosynthetic microsomal mixed-function oxidases--21-hydroxylase, 17 alpha-hydroxylase, and 17,20 desmolase. The deficit in the activities of the first two enzymes resulted in decreased cortisol synthesis with subsequent increased ACTH secretion and adrenocortical hyperplasia. The male pseudohermaphroditism resulted from deficient testosterone synthesis due to deficiency of 17 alpha-hydroxylase and 17,20 desmolase. The mother and two sisters of the affected child had evidence of mild 17 alpha-hydroxylase deficiency.

Rapid chromatographic purification of urinary steroid glucuronates for determination of aldosterone secretion rate

Aldosterone secretion rate (ASR) is utilized as a rapid screening procedure to detect subtle forms of hypertension. A rapid and robust chromatographic method has been developed, based on easily prepared, rigid matrices, which permit the flow of urine by suction through sequential purification columns. Both major metabolites, aldosterone glucuronate and tetrahydroaldosterone glucuronate, are isolated in ca. 75% yield. They are hydrolyzed and quantitated by high-performance liquid chromatography-radioimmunoassay (HPLC-RIA) or, for bulk preparation, further purified by preparative chromatofocusing. These two polar conjugates are isolated in nearly pure form by HPLC on a C2 column with a two-step gradient. An ASR determination can be completed in one to two working days; preparative-scale work takes somewhat longer.

Urinary excretion of immunoreactive vasopressin in prepubertal children. Lack of correlation with urinary excretion of immunoreactive neurophysins

The excretion of immunoreactive vasopressin (AVP) and neurophysins was determined in 24 h urine samples from 62 normal healthy children of various ages. Five groups of children were selected: group I (n = 7, aged 2 to 3 years), group II (n = 13, aged 3 to 5 years), group III (n = 16, aged 5 to 7 years), group IV (n = 16, aged 7 to 9 years), group V (n = 10, aged 9 to 11 years). The method used for urine AVP determination consisted of an extraction using a procedure slightly modified from that of Miller and Moses [14], coupled to a radioimmunoassay. The following urinary AVP excretions were obtained: group I mean: 70.8 ng/m2/24 h range: 51-150 ng, group II mean: 54.1 ng/m2/24 h range: 17-113.6 ng, group III mean: 55.2 ng/m2/24 h range: 18-106 ng, group IV mean: 39.9 ng/m2/24 h range: 11.7-77.9 ng, group V mean: 39.4 ng/m2/24 h range: 25.8-64 ng. The excretion of AVP was significantly correlated to the daily urinary osmolality (P less than 0.001) whether expressed in ng/24 h (r = 0.41) o rin ng/m2/24 h (r = 0.4.7). Neurophysins excretion ranging between 7 and 1,278 ng/24H is too variable to allow interpretation.

Diabetes mellitus and orthostatic hypotension resulting from ingestion of Vacor rat poison: endocrine and autonomic function studies

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Inborn error in the terminal step of aldosterone biosynthesis. Corticosterone methyl oxidase tpe II deficiency in a North American pedigree

Profound salt wasting developed in a male infant who had marked reductions in serum and urinary aldosterone concentrations despite striking hyperreninemia. Coincident elevations in plasma and urinary levels of specific 18-hydroxysteroids localized the defect to corticosterone methyl oxidase Type II, the adrenal enzyme responsible for the final step of aldosterone synthesis. Salt replacement but not hydrocortisone ameliorated the clinical and metabolic abnormalities. Evaluation of 33 other family members disclosed the biochemical disorder in six other subjects who were affected in an autosomal-recessive pattern with variably severe clinical manifestations and abnormal ratios of 18-hydroxycorticosterone (or its metabolites) to aldosterone. This inborn error in aldosterone biosynthesis must be distinguished from other heritable, salt-losing defects in adrenal steroidogenesis.

Prevalence, pathogenesis, and functional significance of aldosterone deficiency in hyperkalemic patients with chronic renal insufficiency

Our findings indicate that hypoaldosteronism occurs commonly (23/31 patients) in hyperkalemic patients with chronic renal insufficiency and that the deficiency of aldosterone contributes to the pathogenesis of the hyperkalemia. In most patients (83%), hypoaldosteronism could be accounted for by deficient renal secretion of renin, but in some patients (17%) overt renin deficiency did not appear to be present, and therefore other (unidentified) causes of aldosterone deficiency must be invoked. The results also indicate that the urinary excretion rate of aldosterone secretion rate in this group of patients.

Hyperreninemia and secondary hyperaldosteronism in pheochromocytomas

Foremost in the differential diagnosis of hypertension is the identification of surgically correctable lesions. Increased plasma renin activity in a hypertensive patient suggests the presence of a renovascular or renal etiology. We have recently seen two adolescent patients whose hyperreninemia was cuased by a pheochromocytoma. Secondary hyperaldosteronism was an associated finding.

Attainment and maintenance of normal stature with alkali therapy in infants and children with classic renal tubular acidosis

Growth was evaluated in a group of 10 infants and children with familial or idiopathic classic renal tubular acidosis in whom alkali therapy was initiated at ages ranging from 8 days to 9.5 yr and administered at dosage schedules documented to sustain correction of acidosis in at least four prolonged observation periods on the Pediatric Clinical Research Ward. When alkali therapy was begun, six patients (four infants and two children) were stunted (height <2.5 SD below mean). Of the four who were not, two infants were too young (<2 wk of age) to have become stunted, and two children had been documented earlier to be nonacidotic. At the start of alkali therapy, the heights of the patients correlated inversely with the maximal possible duration of prior acidosis. WITH SUSTAINED ALKALI THERAPY: (a) each patient attained and maintained normal stature; (b) the mean height of the 10 patients increased from the 1.4+/-4 to the 37.0+/-33 percentile (of a normal age- and sex-matched population); (c) the mean height reached the 69th percentile in the eight patients whose heights could be analyzed according to parental prediction (Tanner technique); (d) the rate of growth increased two- to threefold, and normal heights were attained within 6 mo of initiating alkali therapy in the stunted infants and within 3 yr in the stunted children; (e) the height attained correlated inversely with the maximal possible duration of acidosis (before alkali therapy) only in those patients in whom alkali therapy was started after 6 mo of age, and not in those treated earlier. The amount of alkali required to sustain correction of acidosis increased substantially during the course of treatment in each patient. The maximal alkali requirement ranged from 4.8 to 14.1 meq/kg per day, and in each patient its amount was determined principally by the magnitude of renal bicarbonate wasting.

Amelioration of metabolic acidosis with fludrocortisone therapy in hyporeninemic hypoaldosteronism

In four patients with renal hyperchloremic acidosis and hyperkalemia, hyporeninemic hypoaldosteronism and chronic renal insufficiency (glomerular filtration rates of 13, 31, 35 and 44 ml per minute per 1.73 m2), prolonged administration of fludrocortisone increased urinary potassium and net acid excretion, corrected hyperkalemia and substantially ameliorated acidosis. Except in the patient with the lowest glomerular filtration rate, the increased net acid excretion was due mostly to increased ammonium excretion. Urine pH decreased initially in each patient, but in the three patients with the highest filtration rates, it increased subsequently as ammonium excretion increased, indicating that renal ammonia production increased. Urinary ammonium excretion correlated inversely with serum potassium concentration and did not decrease on discontinuation of therapy if hyperkalemia was prevented from recurring. In patients with renal acidosis and hyporeninemic hypoaldosteronism, administration of mineralocorticoid hormone can augment both renal hydrogen-ion secretion and, by correction of hyperkalemia, renal ammonia production, and thereby ameliorate metabolic acidosis.

Radioimmunological determination of urinary tetrahydroaldosterone

A method is presented for radioimmunological determination of 3alpha, 5beta-tetrahydroaldosterone. It is based upon the reactivity of this steroid with an antiserum induced by the 3-carboxymethyloxime of 18, 21-aldosterone diacetate conjugated with bovine serum albumin. One hundred microliters of urine enzymatically hydrolyzed with an helix pomatia preparation, containing tritiated tetrahydroaldosterone for the yield calculation, were extracted with dichloromethane and chromatographed on a small celite column. The yield after extraction and chromatography was 64 +/- 17%. The radioimmunological determination was carried out in a conventional manner. The method is specific, sensitive (10 pg/tube), exact, reproducible, very simple and extremely rapid. The results showed good agreement with values given by a colorimetric method (p less than 0.001). The median value measured in 45 healthy adult subjects under standard sodium diet was 53.3 microgram/24h (95 % of the population within a 16.6 to 131.1 microgram/24h range). In 78 cases of adrenocortical insufficiency, 60 cases of obesity and 28 cases of hypokalemia, the median values (and the ranges : microgram/24h) were respectively 7.7 (1.0 - 51.0), 80.9 (17.0 - 503.0) and 64.3 (8.0 - 181.0). In 330 hypertensive patients the excretion of tetrahydroaldosterone exceeded the normal range in 115 cases (35%) with a median of 199.7 microgram/24h (131 to 620 microgram/24h).

Concurrent hypercortisolism and hypermineralocorticoidism

Hypertension and hypokalemia occur in patients with Cushing's syndrome whereas aldosterone production is normal and plasma renin activity is usually normal or increased. A normal aldosterone level in the face of suppressed plasma renin activity is unusual and suggests excess mineralocorticoid hormone activity. Our patient, who had Cushing's syndrome due to adrenocortical adenoma, can be classified as having low renin hypertension (suppressed renin and normal aldosterone levels). The mineralocorticoid hormone in excess was deoxycorticosterone which suppressed renin. The aldosterone production was normal and was produced solely by the adenoma. Contralateral adrenal gland suppression of both the zona glomerulosa by deoxycorticosterone via renin, and of the fasciculata by cortisol via ACTH was demonstrated after removal of the adenoma. Normal adrenal function was gradually restored.

Aldosterone and sodium HOMEOSTASIS in preterm infants

A specific mass spectrometric method was used for tetrahydroaldosterone determination in urine of preterm infants (26-34 weeks gestational age) up to 9 weeks of age. Hyponatraemia during the first 2 weeks of life was associated with an excretion of tetrahydroaldosterone (5-50 mug/24 h) comparable with full-term infants. Excretion of tetrahydroaldosterone was significantly elevated in all infants studied during the third week of life (80-350 mug/24 h) and this was associated with establishment of positive sodium balance. The excretion of tetrahydro aldosterone remained high for 2 or 3 weeks. The results are discussed in relation to the development of renal tubules and control mechanism for sodium homeostasis.

Nomograms relating aldosterone excretion to urinary sodium and potassium in the pediatric population: their application to the study of childhood hypertension

The lability and diurnal variation of blood pressure in normal and hypertensive children were examined and found to be less than that described in adults. Nomograms were prepared relating urinary sodium and potassium to urinary aldosterone in children ranging in age from infancy to 22 years. These nomograms reveal that the relation of aldosterone excretion to sodium excretion is described by a hyperbolic function. Most values for normal children, children with mild essential hypertension and children with severe essential hypertension fell between two hyperbolic curves representing the 5th and 95th percentile, respectively. Hypertensive children with low and high plasma renin activity were found to have an inappropriately high level of urinary aldosterone excretion in relation to urinary sodium excretion. No relation was found between potassium and aldosterone excretion. By means of these nomograms the normal standards for aldosterone excretion in children were refined, permitting classification of hypertensive children into distinct groups. This classification may have prognostic significance.

Electrical polarization of rectal mucosa and excretion of tetrahydroaldosterone in patients with cystic fibrosis of pancreas and in normal subjects

The electrical potential difference (PD) across the rectal wall was measured in 26 patients with cystic fibrosis of pancreas (CFP) and in 18 healthy subjects. The PDs obtained in normal children were identical to those previously obtained in normal adults. A significantly greater dispersion of the values was observed in CFP. When the patients were divided into groups according to metachromasia in fibroblast cultures, the mean PD was increased only in the ametachromatic group. True enough, this observation suggests a difference between various forms of CFP, distinguished by metachromasia, and thus is a further indication of the heterogeneity of the disease. The greater abnormalities in metachromasia negative patients may, however, be due solely to the fact that these patients are more severely affected by the disease. The urinary excretion of tetrahydroaldosterone in patients was within the ranges obtained in controls, which excludes the possibility of secondary hyperaldosteronism as the source of increased PD. No evidence was provided in favour of a basic defect in the intestinal transport of Na+ or Cl minus, but K+ concentrations in faecal fluids of patients were significantly lower than in controls. The equilibrium concentration of K+ could be accounted for by simple passive diffusion, suggesting that the epithelium behaved inertly with respect to this ion in CFP.

Plasma aldosterone concentration at delivery and during the newborn period

Aldosterone concentrations in plasma of women on normal sodium intake undergoing cesarean section were 3.7+/-1.4 ng/100 ml (mean+/-1 SD). These values were significantly lower (P < 0.001) than those observed in mothers on normal sodium diet, delivered by the vaginal route (14.9+/-7.0 ng/100 ml). A significant elevation (P < 0.001) of the concentrations was found if the mothers had been on sodium restriction and/or diuretics (44.9+/-24.2 ng/100 ml). In supine position, adult nonpregnant subjects have aldosterone concentrations in plasma of 1.7+/-1.4 ng/100 ml on normal sodium intake and of 16.7+/-8.1 ng/100 ml on low sodium diet.Simultaneous determinations of aldosterone levels in cord blood showed that cord values were significantly higher than those of the corresponding mother (P < 0.01 by paired t test). However, values in cord blood of infants born to mothers on a normal sodium intake were significantly lower (P < 0.005) than those of infants whose mothers had required low sodium diet and/or diuretics during their pregnancy. Aldosterone concentrations in plasma of infants 1-72 hr of age and born to mothers on normal sodium intake were 25.9+/-11.7 ng/100 ml (mean +/-1 SD). These values were significantly lower (P < 0.005) than those of infants born to mothers on restricted sodium intake with or without diuretics (80.3+/-54.4 ng/100 ml). The concentrations at birth were not significantly different from those observed during the first 3 days of life (P > 0.6).