Multicomponent gas chromatographic analysis of urinary steroids excreted by an infant with a defect in aldosterone biosynthesis

Steroid Metabolome Analysis in Disorders of Adrenal Steroid Biosynthesis and Metabolism

Steroid biosynthesis and metabolism are reflected by the serum steroid metabolome and, in even more detail, by the 24-hour urine steroid metabolome, which can provide unique insights into alterations of steroid flow and output indicative of underlying conditions. Mass spectrometry-based steroid metabolome profiling has allowed for the identification of unique multisteroid signatures associated with disorders of steroid biosynthesis and metabolism that can be used for personalized approaches to diagnosis, differential diagnosis, and prognostic prediction. Additionally, steroid metabolome analysis has been used successfully as a discovery tool, for the identification of novel steroidogenic disorders and pathways as well as revealing insights into the pathophysiology of adrenal disease. Increased availability and technological advances in mass spectrometry-based methodologies have refocused attention on steroid metabolome profiling and facilitated the development of high-throughput steroid profiling methods soon to reach clinical practice. Furthermore, steroid metabolomics, the combination of mass spectrometry-based steroid analysis with machine learning-based approaches, has facilitated the development of powerful customized diagnostic approaches. In this review, we provide a comprehensive up-to-date overview of the utility of steroid metabolome analysis for the diagnosis and management of inborn disorders of steroidogenesis and autonomous adrenal steroid excess in the context of adrenal tumors.

Profiling steroid hormones and urinary steroids

This paper reviews techniques utilized in the profiling of steroids in body fluids and tissues. Methods for profiling plasma unconjugated steroids and urinary steroid metabolites are focused on. Concentrations or levels of excretion of a variety of steroids have been documented and reviewed. The importance of profiling techniques in the study of normal and pathophysiology of hormonal steroids is discussed.

Improved gas chromatographic-mass fragmentographic assay for tetrahydroaldosterone and aldosterone in urine

A newly devised procedure for a simultaneous determination of urinary tetrahydroaldosterone and aldosterone is described. The procedure is based on deconjugation and acetalization, followed by extraction and derivatization of the urinary compounds to their trimethylsilyl ethers and subsequent gas chromatographic-mass fragmentographic detection. To evaluate the assay, aliquots of a urine sample of a healthy individual were analysed in multiplicate; a mean tetrahydroaldosterone concentration of 103 nmol/l and a within-sample, within-day- and day-to-day coefficient of variation of 1.8, 3.2 and 3.4%, respectively, were found. Determination of aldosterone in the same sample yielded a mean concentration of 25.3 nmol/l and the following coefficients of variation: 2.8% (within-sample), 3.8% (within-day) and 4.3% (day-to-day). The urinary excretion of tetrahydroaldosterone and aldosterone in 24-h urine portions was determined in twenty healthy individuals, aged 23-77 years; for tetrahydroaldosterone and aldosterone, an excretion of 94 +/- 66 nmol per 24 h and of 40 +/- 22 nmol per 24 h was found, respectively, in accord with the literature. An example of the usefulness of the described assay is given by establishing the cause of severe salt-wasting in an infant; a highly elevated tetrahydroaldosterone and aldosterone excretion was demonstrated, proving that the child suffered from unresponsiveness to aldosterone (pseudohypoaldosteronism).

Disorders of the adrenal cortex: their effects on electrolyte metabolism

The adrenal cortex is an important factor in the control of electrolyte and water balance and in blood pressure homeostasis. Not surprisingly, therefore, hyper- and hyposecretion of one or more of its products has extensive repercussions. Hypersecretion of aldosterone, as seen in primary hyperaldosteronism and related diseases, and of other mineralocorticoids such as corticosterone and/or 11-deoxycorticosterone, as seen in 17 alpha-hydroxylase deficiency or 11 beta-hydroxylase deficiency syndromes, respectively, are associated with hypertension, sodium retention, potassium wastage and a metabolic alkalosis. On the other hand, impaired secretion, as in Addison's disease or in congenital deficiencies of other steroid-synthesizing enzymes, leads to hypotension, sodium loss with hypovolaemia, and hyperkalaemia. In each case, these disturbances of electrolyte metabolism may cause neurological and muscle dysfunction. The relationship between glucocorticoid hypertension and electrolyte metabolism is less clear and the importance of the adrenal cortex in the aetiology of essential hypertension is still being assessed.

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.

Renin-angiotensin-aldosterone system

There is increased activity of the renin, angiotensin, aldosterone (RAA) system in infancy and childhood. An inverse relationship between plasma renin, aldosterone and age has been demonstrated. In childhood hypertension due to renovascular disease or pyelonephritic scarring peripheral plasma renin is increased. Renal vein renin measurements in children with renal hypertension have proved valuable in predicting surgical curability of the underlying lesion. The upper limit of normal for the renal venous renin ratio in normotensive children without renal disease is 1.5. Pharmacological blockade of the RAA system has a place in diagnosis and treatment of hypertensive children. The plasma renin aldosterone profile is diagnostically useful in the investigation of salt-wasting disease and can easily distinguish between aldosterone biosynthetic defects and pseudohypoaldosteronism.

Pseudohypoaldosteronism

10 infants are described with pseudohypoaldosteronism, 5 in detail and a further 5 briefly. They all presented with hyperkalaemia, urinary salt-wasting disease, and ostensibly normal renal and adrenocortical function. Diagnosis was established by demonstrating the greatly increased values of plasma renin activity and plasma aldosterone concentration, plus the increased excretion of aldosterone and its metabolites on gas chromatographic and mass spectrometric analyses of urine. The children were treated with sodium chloride supplements, up to 60 mmol/day, but by the time most of the infants were about a year old these could be stopped. Exogenous mineralocorticoids were without effect in those to whom they were administered. The precise aetiology of the condition remains conjectural; lack of renal tubular response to aldosterone seems probable. Pseudohypoaldosteronism may be more common than has been thought and new techniques for investigating salt-wasting disorders may show its true incidence.

Salt-losing syndrome in 2 infants with defective 18-dehydrogenation in aldosterone biosynthesis

Two infants presented with a salt-losing syndrome, the presenting features of which were subtle. One case appeared to be transient. Deficient production of aldosterone was shown by plasma renin activity and plasma aldosterone profile. Gas chromatography-mass spectrometry of urine indicated a defect in 18-dehydrogenation of 18-hydroxycorticosterone. Treatment with salt supplements and 9alpha-fludrocortisone reversed the salt-losing state and in one case treatment was later stopped. Although the disease may appear transient, the biochemical defect is persistent and for adequate growth a positive salt-balance is necessary.

Selective hypoaldosteronism in Iranian Jews: An autosomal recessive trait

A salt-wasting syndrome associated with high plasma renin activity and inappropriately low aldosterone levels was observed among eight Jewish families from Iran. Aldosterone deficiency was due to an inborn error selectively involving the terminal portion of the bio-synthetic pathway and characterized by an enzymic block in the conversion of 18-hydroxy-corticosterone to aldosterone. The analysis of the eight pedigrees, including 12 affected children, shows a high coefficient of inbreeding. Genetic analysis, by two independent methods, strongly suggests an autosomal recessive mode of transmission of the syndrome.