GH secretion in thalassemia patients with short stature

Osteoporosis syndrome in thalassaemia major: an overview

Osteoporosis in thalassaemia major (TM) represents a prominent cause of morbidity. The mechanism of pathogenesis of bone disease (BD) in TM is multifactorial and complicated. Peak bone mass is achieved shortly after completion of puberty and normally remains stable until the third decade of life when age-related bone mass begins. Growth hormone (GH) and sex steroids play a crucial role in bone remodeling and in the maintenance of skeletal architecture during adult life. GH and insulin growth factors (IGFs) have anabolic effect in bone formation. Sex steroids act probably by increasing the expression of RANKL by osteoblastic cells and alterations in the RANK/RANKL/OPG system in favor of osteoclasts. Impaired GH secretion and lack of sex steroids in thalassemic patients due to pituitary damage, contribute to failure of achieving optimal peak bone mass. Other endocrine complications such as hypoparathyroidism and vitamin D deficiency have also a detrimental role on bones in TM. It is still questionable whether the international criteria for defining osteopenia and osteoporosis are relevant to patients with TM; also a question arises for the diagnostic methods such as DEXA scan and management of osteoporosis with known treatment protocols, in the thalassaemic patient.

Screening of growth hormone deficiency in short thalassaemic patients and effect of L-carnitine treatment

INTRODUCTION

Evaluation of growth hormone (GH) in short thalassaemic patients and effect of L-carnitine therapy in those with hormone deficiency.

MATERIAL AND METHODS

The study included 30 β-thalassaemic patients aged 13.8 ±1.7 years and 30 children with constitutional short stature as controls. Anthropometric measurements (basal and after 6 months), thyroid profile, insulin-like growth factor-1 (IGF-1) and GH provocation by 2 tests were carried out. Eight patients with inadequate GH response to both clonidine and ITT were given L-carnitine treatment for 6 months. They were re-evaluated (clinically, anthropometrically and in the laboratory by doing GH stimulation test) after 6 months of therapy.

RESULTS

Twelve (40%) patients had sub-clinical hypothyroidism and 10 (33.3%) had growth hormone deficiency (GHD). Peak GH and growth velocity (cm and standard deviation score [SDS]) were significantly lower while weight (SDS) and weight/height SDS were significantly higher than in patients with constitutional short stature (p < 0.05). A significant positive correlation was found between height and target height (cm). Haemoglobin levels, peak GH, IGF-1 and growth velocity (cm & SDS) were significantly higher and the number of blood transfusions was significantly lower in GH deficiency patients after L-carnitine treatment (p < 0.05). Delta changes were higher in height (cm & SDS), estimated mature height and sitting height and lower in target height - height (SDS and cm) six months after L-carnitine treatment in β-thalassaemic patients with GHD (p < 0.05).

CONCLUSIONS

Growth hormone deficiency is an aetiological factor in thalassaemic patients with short stature. L-carnitine can promote GH secretion and growth.

Growth and endocrine function in thalassemia major in childhood and adolescence

BACKGROUND

Thalassemia major is an inherited hemoglobin disorder characterized by chronic anemia and iron overload due to transfusion therapy and gastrointestinal absorption. Iron overload causes most of the associated mortality and morbidity and frequently involves the endocrine glands.

AIM

To review the most pertinent literature on the topic.

METHODS

One hundred and twenty-three papers were evaluated.

RESULTS

Disproportionate short stature is frequent and becomes more evident at puberty because of the lack of growth spurt. Later on, partial height recovery may occur. Long-term treatment with recombinant human GH seems ineffective to improve final height. Pubertal development is characterized by a clinical spectrum ranging from hypogonadism to a simple delay in starting and developing of puberty. Hormonal replacement is mandatory in cases of absent or arrested puberty. Pancreatic beta-cells function may be impaired during adolescence or later on. Its impairment ranges from hyperinsulinemia, secondary to insulin resistance, with normal glucose tolerance to beta-cells failure with insulin-dependent diabetes mellitus. Primary hypothyroidism may affect thalassemic patients from the second decade of life. The thyroid dysfunction may be reversible (if an intensive chelation therapy regimen is started in the precocious phase), stationary, or slowly progressive. Central hypothyroidism is less common and autoimmune thyroiditis absent.

CONCLUSION

Despite the improvement of the treatment, the involvement of the endocrine system still burdens the life of these patients. Further therapeutic improvement would reasonably reduce morbidity and, hopefully, mortality of thalassemic patients and make the endocrine disorders easier to treat.

Thalassaemia and aberrations of growth and puberty

Endocrine dysfunction in Thalassaemia major (TM) is a common and disturbing complication, which requires prompt recognition and treatment. The contribution of the underlying molecular defect in TM to the development of endocrinopathies is significant because the patients with the more severe genetic defects have a greater rate of iron loading through higher red cell consumption. TM patients frequently present delay of growth and puberty with reduction of final height. The pathogenesis of growth failure is multifactorial and is mainly due to chronic anemia and hypoxia, chronic liver disease, zinc and folic acid deficiency, iron overload, intensive use of chelating agents, emotional factors, and endocrinopathies (hypogonadism, delayed puberty, hypothyroidism) and GH-IGF-1 axis dysregulation. Although appropriate iron chelation therapy can improve growth and development, TM children and adolescents treated intensively with desferrioxamine remain short as well, showing body disproportion between the upper and lower body segment. Body disproportion is independent of pubertal or prepubertal period of greater height gain. Treatment with recombinant GH (rhGH) is recommended when GH deficiency is established, and even so, the therapeutic response is often non satisfactory. Growth acceleration is mostly promoted with sex steroids in children with associated pubertal delay. Sexual complications in TM, which include Delayed Puberty, Arrested Puberty and Hypogonadism, present the commonest endocrine complication. Iron deposition on gonadotroph cells of the pituitary leads to disruption of gonadotrophin production which is proven by the poor response of FSH and LH to GnRH stimulation. In the majority of patients gonadal function is normal as most women with Amenorrhea are capable of achieving pregnancy with hormonal treatment and similarly men with azoospermia become fathers. Secondary Hypogonadism appears later in life, and is manifested in women as Secondary Amenorrhea and in men as decline in sexual drive and azzoospermia. The damage to the hypothalamus and pituitary is progressive, even when intensive chelating therapy is given and the appearance of Hypogonadism in both sexes is often unavoidable. Close follow up and proper management is crucial for every patient with TM. Early recognition of growth disturbance and prevention of hypogonadism by early and judicious chelation therapy is mandatory for the improvement of their quality of life. Patients with TM can now live a better life due to modern advances in their medical care and our better understanding in the pathogenesis, manifestation and prevention of endocrine complications.

Growth of children with beta-thalassemia major

Hypertransfusion and regular chelation therapy have allowed improved survival in patients with thalassemia major (TM). Despite medical advances, growth failure and hypogonadism remain significant clinical problems in these patients in adolescence. Disproportionate truncal shortening which is common especially among adolescents with thalassemia, is due to platyspondyly resulting from a combination of factors like hemosiderosis, desferrioxamine toxicity or deficiency of trace elements. Although growth hormone (GH) deficiency and GH neurosecretory dysfunction have been described in TM patients, most short TM patients have normal GH reserve. The low serum IGF-1 and IGFBP-3 concentrations in TM patients despite having normal GH reserve and serum GH binding protein levels suggest that a state of secondary GH insensitivity exists. The pubertal growth spurt may be impaired in TM patients going through spontaneous or induced puberty and may have a negative effect on final adult height. GH therapy in dosages ranging from 0.5-1.0 IU/kg/wk has resulted in a significant improvement in growth velocity in short TM children without any adverse effects on skeletal maturation, blood pressure, glucose tolerance and serum lipids. There is limited evidence that GH treatment can result in an improved final adult height in short TM children. Careful and regular clinical and biochemical monitoring should be preformed on these patients while they are treated with GH.

Clinical management of beta-thalassemia major

Management of patients with beta-thalassemia is based on adequate, safe blood transfusions (free of transfusion-transmitted diseases) and prevention of iron overload. Iron overload causes multiple endocrinopathies, contributes to osteoporosis, and is the cause of cardiac disease. Cardiac disease, secondary to iron damage, causes death in developed countries as a result of noncompliance to deferoxamine from the third decade of life. In underdeveloped countries, cardiac death starts from 12 years of age, due to nonavailability of deferoxamine. With the emergence of the advanced cardiac magnetic resonance imaging technique, early diagnosis of heart iron will allow the currently available iron-chelating agents (oral and parenteral) to be used in an innovative way to improve the quality of life and improve survival of patients with beta-thalassemia.

Endocrine complications of thalassemia

Growth, sexual development, fertility, bone mineral density, diabetes mellitus, hypothyroidism, hypoparathyroidism, and hypoadrenalism are the main issues to be addressed in the long-term follow-up of patients with thalassemia. During childhood, growth may be affected by anemia, and other potential endocrine complications. Puberty is the stage of the maximal growth insult. Beta thalassemia is associated with bone abnormalities characterized by bone marrow expansion of the medullary cavity, and osteopenia with cortical thickening and trabecular coarsening. Good nutrition with adequate vitamins and trace elements intake, along with calcium and vitamin D supplementation, can increase bone density and prevent bone loss. Endocrine abnormalities should be monitored carefully and a thorough endocrine evaluation should be carried out yearly in every patients to detect subclinical endocrinopaties.