Dr. Julio Libman
Although stunting or short stature cannot be absolutely defined, a child is considered short when his height is below the third percentile, which corresponds to approximately two standard deviations from the normal mean. By saying that it is below the third percentile, it indicates that, out of every 100 normal children of the same age, sex, and race, there are three who are shorter, or, in other words, there are ninety-seven who are taller.
Physiology and phytopathology. Normal growth is the result of the interaction of numerous intrinsic and extrinsic factors on the genetically determined self-growth capacity of the body's cells. The short arm of the X chromosome and autosomes carry genetic determinants of growth. Proper nutrition is essential for optimal somatic growth and ripening. Energy sources, total calories and oxygen supply appear to be critical factors for cell multiplication; Protein intake must be adequate both in terms of the total amount and the provision of essential amino acids. Vitamins A and D are important growth factors, like some metals, because of their role as cofactors of enzyme activity. The action of the enzymes requires, on the other hand, the maintenance of the pH at the optimum level. Normal neuromuscular activity is necessary for limb development. The general level of activity is likely to influence growth. Different hormones act as essential catalysts for the normal and harmonious development of growth. In this sense, it is worth highlighting the action of somatotropin, thyroid hormones, insulin and sex steroids, which would have some role in the acceleration of growth that occurs at puberty. The action of somatotropin is mediated by somatomedins, polypeptides produced in the liver and probably in other tissues where they would act locally, and whose levels would also be dependent on other hormones and the general state of nutrition.
When the doctor is consulted for a short stature problem, his first task is to determine if the condition is real or imagined, if it is below the third percentile for the corresponding age and sex, and if there has been a decrease in the speed of growth, which can be determined from the size of the clothes, from the comparison with siblings or companions, and less frequently in practice, by direct measurements. Most patients with short stature do not have demonstrable diseases, be they endocrine or otherwise. The cause, when detectable, can be determined by clinical features and complementary tests. Particular attention should be paid to the family history of pubertal growth and development, evolution of pregnancy, weight and height at birth,
Although longitudinal growth is the most easily observable, it is essential, as already mentioned, to consider body proportions, feature maturation, dental development, and skeletal maturation. The final height to be reached obviously depends not only on the growth rate but also on its duration; therefore, height should be evaluated based on bone maturity (bone age).
The clinical features that can be observed and that can be associated with short stature are shown in Figure 22-1.
Measurement of the patient: Proper and correct evaluation of height and growth rate are essential in the study of growth disorders. Measurements should always be carried out using the same technique: without shoes and in the correct position, standing in “attention position”, heels almost together, touching the same vertical plane with the gluteal area, shoulders and occiput, flat abdominal muscles , and the lower rim of the orbit in the horizontal plane passing through the external auditory meatus. Measurements should be made at approximately the same time to avoid diurnal variations resulting from postural changes and vertebral crush. The decrease in height between the first hours of the morning and the last hours of the afternoon is, on average, 15 millimeters. The results obtained at regular intervals of three months, and for periods of at least one year, are compared with those of a control population of the same age and sex using special graphs; In this way, it is possible to obtain a longitudinal growth curve of the patient in that period, as well as observe deviations in relation to the initial percentile.
Body proportions: The lower segment of the skeleton, measured in an upright position, is defined as the distance between the upper edge of the pubic symphysis to the floor, while the upper segment is obtained by subtracting the lower one from the total height. Body proportions change with growth. At birth the limbs are relatively short and there is therefore a ratio of approximately 1.70 between the upper (vertex-pubis distance) and inferior (pubis-plant distance) body segments. Between the ages of 9 and 10, the proportionally greater growth of the limbs makes this ratio 1, remaining constant in adult life. There are special tables that indicate the normal proportions for each age and sex. A patient presents a delay of harmonic growth when, having short stature,
An example in this regard is patients with genetic deficit or due to lack of somatotrophin. On the contrary, the delay of disharmonic growth implies the maintenance of more infantile proportions, corresponding to a younger chronological age. Examples of this are in hypothyroidism, achondroplasia, and hypophosphatemic rickets.
Weight: There are graphs that relate weight to chronological age. If growth is impaired by malnutrition, in celiac disease, for example, weight is likely to be reduced even more than height.
Maturation of the traits: The configuration of the facies is an important indicator of the degree of maturity. For example, growth of the root of the nose is decreased during childhood in hypothyroidism and explains the characteristically immature facies of childhood hypothyroid glands of a certain time of evolution. This parameter can be evaluated by measuring the interorbital distance.
Dental development: The dental growth process can be evaluated by direct inspection or by radiographs. Both primary and secondary dentition are affected by factors similar to those that influence bone maturity.
Causes of short stature
They are listed in Table 22-1.
Table 22-1. Causes of short stature.
Considering the etiologies of short stature as a whole, endocrine causes are the least frequent. Even taking into account those children whose height is below the third percentile, or whose growth rate is below normal (annual average of 5 to 8 centimeters from 3 to 12 years), which leads to a progressive deviation of the physiological growth curve, only a very small percentage will have a demonstrable somatotrophin deficiency. In addition to the tendency to fat accumulation, due to the lack of lipolytic action of growth hormone, patients with an isolated deficiency of this hormone usually have a micropenis and a high voice due to laryngeal hypoplasia. Statural and bone ages suffer a similar delay. Rarely, episodes of hypoglycaemia occur, due to lack of the hypoglycemic effect of somatotrophin. Its deficiency can be accompanied by a decrease in the production of other anterohypophyseal hormones, in the case of tumors or by idiopathic (autoimmune?) Insufficiency. Neurological symptoms such as headaches and visual field disturbances are usually the first signs of an adenoma, craniopharyngioma, or other tumors, while growth retardation is the first manifestation in the idiopathic form.
Other endocrine disorders can be associated with poor height, including chronically decompensated diabetes mellitus (insulin is essential for growth) and chronic adrenal insufficiency. The excess of endogenous glucocorticoids due to hyperplasia or adrenal tumors, or exogenous due to chronic administration, responsible for Cushlng syndrome, is short of stature, which is produced through multiple mechanisms, such as catabolic action on proteins and the inhibition of somatotrophin secretion and somatomedin production. Patients with hypothyroidism may present to the office with weight gain due to myxedema infiltration, decreased growth rate and short stature. Hypothyroidism causes a greater delay in bone age than in stature,
Any chronic general disease can result in decreased growth, both in the newborn and in the child or adolescent. Intrauterine growth retardation can limit maximum height, although the postnatal growth rate is normal, especially if the birth weight is less than 2.5 kilograms. Hypoxia determined by cardiopulmonary diseases can decrease the tissue response to normal amounts of circulating hormone. Somatomedin levels may be subnormal in patients with severe liver disease, and somatomedin inhibitors may be present in the circulation in patients with poorly controlled kidney disease and nephropathy and diabetes mellitus. Chronic malnutrition states can contribute to a low production of this last hormone. A rare and reversible form of functional hypopituitarism is psychosocial dwarfism, or maternal deprivation syndrome, which occurs in circumstances of an abnormal parent-child relationship, and which improves by removing the child from the adverse family environment. Malabsorption syndromes may, at times, not be clinically very evident, and in such cases special studies are required to detect them.
Most chondrodystrophies and skeletal aberrations that cause short stature produce a disproportionate picture of dwarfism. Chromosomal abnormalities frequently present a characteristic phenotype, as can be seen in Tumer's syndrome, an alteration that is genetically determined and characterized by ovarian agenesis with deletion of an X chromosome (45 XO karyotype) and absence of nuclear chromatin (corpuscle Barr negative). There may be incomplete forms with mosaicism (XG / XX, XO / XXX, XO / XX / XXX), in which case the chromatin may be positive. Tumer's syndrome presents with short stature, lack of pubertal development with primary amenorrhea, neck of the sphincter due to the existence of an achromiomastoid fold, valgus ulna, edema of the back of the hand, short fourth metacarpal,
The evaluation of a boy who consults for short stature requires ruling out systemic diseases first and, in the case of a girl, gonadal dysgenesis or Tumer syndrome. After a careful history and clinical evaluation, a series of tests will be requested: complete blood count, ingestion, urea, creatinine, proteinogram, calcaemia, phosphataemia, alkaline phosphatase, blood ionogram, blood glucose, complete urine and a nuclear chromatin in a cell smear. of the jugal mucosa and polymorphonuclear leukocytes. Radiological studies include a face and profile skull x-ray, focused on the sella turcica, and a hand and wrist plate to determine bone age.
The endocrinological evaluation includes the quantification of thyroxine (T4) and thyroid stimulating hormone (TSH) and, if the clinical picture is justified, that of somatomedin and a stimulus test to determine the somatotrophic reserve. Next, reference will be made to bone age and the quantification of growth hormone and somatomedin.
Bone maduration. There are several methods to assess bone maturation. The most widely used is the Greulich and Pyle atlas method, which evaluates an anteroposterior radiograph of the left hand and wrist. Skeleton maturity is expressed as bone age or skeletal age. Bone age is the age at which the degree of bone maturation observed would be typical. Radiography can also reveal the unexpected presence of bone dystrophies or disturbances of ossification.
Each ossification nucleus appears at a certain age. Thus, for example, newborns present in 100% of cases the Béclard nucleus in the lower extremity of the femur, and in 80% the nucleus of the cuboid. The pisiform makes its appearance at 11 years old in men and 9 years old in women. Delayed bone age is observed in hypothyroidism, somatotrophin deficiency, malnutrition states, and idiopathic growth and pubertal retardation. In this table, which is observed almost exclusively in men, there is a slower growth rate than usual, which continues for a longer time, with a later but normal pubertal development, as well as the final height.
Plasma somatotrophin. A single determination of plasma somatotrophin is of no value in the diagnosis of hyposomatotrophism, since there may be a wide overlap of values between normal people and patients with hypopituitarism, there being no precise limit between both groups. In such cases, various stimuli must be used which, acting hypothalamically, release somatotrophin. Two different tests must be carried out, since a normal individual may respond to one type of stimulus and not another, and the same stimulus may or may not respond on different occasions.
Insulin hypoglycemia test and l-dopa test. Under normal conditions, hypoglycemia and l-dopa lead to an increase in somatotrophin, which does not occur in cases of deficiency of the latter hormone.
Somatomedin C. This peptide, produced in the liver by somatotrophic action, can be measured by radioimmunoassay. In interpreting the results, it is necessary to take into account the age of the patient.