What is the most appropriate investigation for a patient with acromegalic features, including a large head and hands, and lower limb pains, who has difficulty fitting through doors?

From the Guidelines

The most appropriate investigation for this patient is not explicitly listed among the provided options, but based on the clinical presentation suggestive of acromegaly, the best initial step would involve assessing for a pituitary adenoma, typically through imaging such as MRI sella with and without IV contrast, as recommended by recent guidelines 1. However, given the options provided (a. Alkaline phosphatase, b. Ionized calcium, c. U&Es, d. TFTs, e. ACE, f. LFTs), ionized calcium (option b) is the most relevant initial laboratory investigation because acromegaly can be associated with hypercalcemia due to increased parathyroid hormone-related peptide production, and multiple endocrine neoplasia type 1 (MEN1) can present with both acromegaly and primary hyperparathyroidism, making calcium levels diagnostically valuable 1. Key points to consider in the management of acromegaly include:

• The condition is usually caused by a GH-secreting pituitary adenoma.
• Management involves suppressing GH hypersecretion, reducing IGF-I levels, and controlling tumor growth.
• Multimodal treatment is often required, including surgical, pharmacological, and radiotherapeutic approaches.
• Comorbidities such as left ventricular hypertrophy, hypertension, and obstructive sleep apnea should be managed as they are in the general population.
• Monitoring and management of glucose metabolism are important, especially when using certain medications for acromegaly. Given the clinical context, while the provided options do not directly address the need for pituitary imaging or direct assessment of GH/IGF-1 levels, ionized calcium (option b) offers a relevant initial step in evaluating potential endocrine abnormalities associated with acromegaly.

From the Research

Diagnosis of Acromegaly

The patient's symptoms, such as a very large head and hands, and lower limb pains, suggest acromegaly. To confirm the diagnosis, the following investigations are relevant:

• Serum insulin-like growth factor 1 (IGF-1) measurement is recommended as the initial screen for patients with suspected acromegaly 2
• The gold standard diagnostic test remains the oral glucose tolerance test with concomitant growth hormone (GH) measurement 2
• Among the given options, none directly measures IGF-1 or GH levels. However, alkaline phosphatase (option a) can be elevated in acromegaly due to increased bone turnover 3, 4, 5

Investigation Options

Considering the options provided:

• Alkaline phosphatase (option a) may be elevated in acromegaly, but it is not a specific diagnostic test for the condition
• Ionized calcium (option b) is not directly related to the diagnosis of acromegaly
• U&Es (option c) and LFTs (option f) are not specific for acromegaly
• TFTs (option d) may be relevant in some cases of acromegaly, as thyroid dysfunction can occur, but it is not the primary diagnostic test
• ACE (option e) is not directly related to the diagnosis of acromegaly

Given the options, alkaline phosphatase (option a) may be the most relevant investigation, although it is not a definitive diagnostic test for acromegaly. A more specific diagnostic approach would involve measuring IGF-1 levels and performing an oral glucose tolerance test with GH measurement, as recommended in the studies 3, 4, 5, 6, 2