The External Genitalia, Bone Age And Laboratory Investigations In Endocrine Diseases Manifestations
External Genitalia And Bone Age
State of development of the external genitalia gives indication of the hormonal status in the early development period. Fusion of the labia and enlargement of the clitoris in female babies with or without formation of a penile urethra at birth, are indicative of excessive androgenic activity during early fatal development. Development of clitoromegaly is the result of androgen over-activity later in life. Pelvic examination is necessary for the assessment of the size of the uterus and ovaries and vaginal development. Examination of vaginal epithelim and cervical mucus gives evidence of activity of the ovarian hormones.
Small penis (less than 2.5 cm in length and flaccid) may be due to abnormalities of testosterone biosynthesis, organ unresponsiveness, gonadal dysgenesis, hypoethalamo-pituitary disorders or rarely defective development. Testicular size is objectively assessed by measurement. Noraml adult testis measures 5.0+0.8cm and it has a volume of 15 ml. The testes are small and firm in Klinefelter’s syndrome whereas they are small and soft in acquired testicular atrophy.
This is a common parameter used for assessing the maturity of the skeleton. Appearance of the centers of ossification and fusion of epiphyses occur regularly at definite periods during the growth of the individual. These are under hormonal control. Abnormalities in the growth of the skeleton provide evidence of endocrine dysfunction. Radiographs of selected bones are routinely done for this purpose. In hypothyroidism occurring in early life centers of ossification fail to appear. Cushing’s syndrome, hypopituitarism and hypogonadism lead to delay in epiphyseal fusion. The epiphyses appear and fuse prematurely in hyperthyroidism and sexual precocity.
Laboratory Experiements On Hormones
Laboratory Investigation In Endocrine Disorders
The function of any endocrine gland can be assessed by:
- Quantitative estimation of its hormones and their metabolites;
- Biochemical tests which reflect the metabolic abnormality, e.g. blood sugar in diabetes mellitus, serum calcium in parathyroid disorders;
- Imaging procedures which reveal the anatomy and function of the endocrine glands and other tissues; and
- Assessment of the functional reserve of the glands by appropriate stimulation and suppression tests.
Quantity of hormones and their metabolites in body fluids: The levels of hormones in blood and body fluids are very small. Non-peptide hormones are present in body fluids in concentration of microgram (10-6g) whereas peptide hormones are present only in the range of nanograms (10-9g) or pictograms (10-12g) per unit volume. Several techniques are used for their estimation. These are:
- Spectrophotometric and fluorimetric assay,
- Radioimmunoassay (RIA), and
- Enzyme-linked immunosorbent assay (ELISA).
Adrenal steroids like plasma cortisol and its metabolites- 17-ketosteroids, 17-ketogenic steroids and 17-hydroxysteroids are estimated by spectrophotometric analysis. Radioimmunoassay (RIA) is the most extensively used method for quantitation of hormones in clinical practice. By this method almost all hormones can be estimated.
Enzyme-linked immunosorbent assay (ELISA) is used instead of RIA in many cases. Though ELISA has some advantages over RIA, so far ELISA has not been able to achieve the type of exquisite sensitivity required for measuring pictogram quantities of substances and therefore many hormones cannot be estimated by this technique.
Imaging of endocrine glands is done in several ways. Imaging techniques are employed when surgical or other methods of ablative therapy are contemplated. Commonly used procedures are:
- Radiography-plain and contrast studies.
- Isotope scanning
- Ultrasound scanning, and
- Computerized tomography
The hormone secretion from these glands can be estimated by selective catheterization of their efferent veins. On a final note, another very important laboratory investigation are the stimulation and suppression tests. These are useful to assess the functional reserve and autonomy of the different endocrine glands and integrity of their feed back control.
© 2014 Funom Theophilus Makama