12th April 2024

Causes of excessive growth

Acromegaly

Acromegaly is an endocrine disorder characterised by the excess of growth hormone production. Typically caused by pituitary gland tumours or hyperplasia, it can also be a result of ectopic production from other sources, such as carcinoid tumours. Common signs and symptoms include excessive growth of hands (spade hands), feet and tongue, tired demeanour involving puffy facial features, coarsening of the face and supraorbital ridges, reduced libido, obstructive sleep apnoea and arthralgia. Gigantism, a form of acromegaly in children, occurs due to excessive growth before the completion of epiphyses fusion. Acromegaly increases the risk of colon cancer, IHD, CVA and diabetes.

Investigations

Serum IGF-1 is used as an initial screening test and is more reliable than GH as it can vary during the day. The oral glucose tolerance test (OGTT) is used to confirm after a positive screening test. It consists of fasting the patient overnight and giving glucose supplementation in the morning with serial GH measurements, as glucose should inhibit GH. A diagnosis is made if the glucose load does not suppress GH <1 microgram/litre. All these tests can be affected by puberty, pregnancy, anorexia, liver/renal diseases or diabetes.

An MRI scan of the pituitary and hypothalamus may demonstrate a tumour. Visual field testing allows assessment for any abnormalities and echocardiography for acromegaly-associated cardiomyopathies.

Management

The management consists of removing the tumour, with the majority having transsphenoidal surgery. Medical therapy can be undertaken with or without prior surgery and includes somatostatin analogues (octreotide/lanreotide) and GH antagonists (pegvisomant). In select patients with aggressive disease or when medication is ineffective, radiotherapy can also be considered.

Marfan syndrome

A genetic connective tissue disorder affecting the production of fibrillin. It follows an autosomal dominant pattern, affecting FBN1 gene on chromosome 15. Typical presentation includes excess long bone growth causing dolichostenomelia (disproportionate extremity to trunk length), joint laxity (pectus carinatum/excavatum, pes planus, acetabular protrusion/hip dislocations), arachnodactyly and ectopia lentis (upwards dislocated lens). Due to abnormal elastic fibre formation, patients are at increased risk of several cardiac pathologies, such as aortic regurgitation, mitral valve prolapse and dilatation/dissection of vessels. Management involves investigating and monitoring for cardiac pathologies with echocardiography, CT and MRI. Beta-blockers are used to reduce myocardial contractility and pulse pressure and lower the risk of aortic dilatation. Elective repair or replacement is also considered.

References

• Adigun, O., Nguyen, M., Fox, T. and Anastasopoulou, C., 2022. Acromegaly. [online] Ncbi.nlm.nih.gov. Available at: <https://www.ncbi.nlm.nih.gov/books/NBK431086/>
• Longmore, J., Wilkinson, I., Baldwin Andrew and Wallin Elizabeth., 2014. Oxford handbook of clinical medicine. 9th ed. Oxford: Oxford University Press, pp.230-231
• Salik, I. and Rawla, P., 2022. Marfan Syndrome. [online] Ncbi.nlm.nih.gov. Available at: https://www.ncbi.nlm.nih.gov/books/NBK537339/
• Longmore, J., Wilkinson, I., Baldwin Andrew and Wallin Elizabeth., 2014. Oxford handbook of clinical medicine. 9th ed. Oxford: Oxford University Press, p.720.