Evaluation of the Muscular and Cutaneous Sodium Storage by 23Na MRI in Patients With Chronic Adrenal Insufficiency

Evaluation of the Muscular and Cutaneous Sodium Storage by 23Na MRI in Patients With Chronic Adrenal Insufficiency

Evaluation of the Muscular and Cutaneous Sodium Storage by 23Na Magnetic Resonance Imaging in Patients With Chronic Adrenal Insufficiency Compared to Healthy Subjects

This study investigates the sodium content in the calf muscle and the skin obtained via 23Na-magnetic resonance imaging in patients with chronic adrenal insufficiency compared to healthy controls.

Patients with chronic adrenal insufficiency depend on lifelong glucocorticoid and mineralocorticoid replacement therapy. Monitoring is based on clinical and laboratory parameters reflecting hemodynamic stability, electrolyte status and plasma renin concentration. Reduced subjective well-being is however often described by these patients in absence of clinical or laboratory abnormalities and is thus a strong indicator of the gap between the concept of adequate hormone substitution and patients' requirements. This study investigates the sodium content in the calf muscle and the skin obtained via 23Na-magnetic resonance imaging (MRI) in patients with chronic adrenal insufficiency compared to age-, sex- and BMI- matched healthy controls. The aim of the study is to evaluate the potential role of 23Na-MRI for monitoring of hormone replacement by investigating tissue sodium concentrations in patients with adrenal insufficiency.

A 23Na magnetic resonance imaging of the calf (muscle and skin) was performed in every participating patient after clinical and laboratory examinations.

Imaging/diagnostic: Evaluation of the muscular and cutaneous sodium storage by 23Na magnetic resonance imaging. 23Na magnetic resonance imaging: 23NA-MRI protocol on a 3T scanner (Magnetom PRISMA, Siemens, Erlangen) implementing a 3D sequence.

Assessment of the sodium content of the calf muscle. Relative sodium signal intensities were calculated as ratio of tissue sodium intensity and the intensity of a vial containing a concentration of 100mmol/l.

Assessment of the sodium content of the calf skin. Relative sodium signal intensities were calculated as ratio of tissue sodium intensity and the intensity of a vial containing a concentration of 100mmol/l.

Inclusion Criteria: Age > 18 years Written informed consent Chronic adrenal insufficiency (first diagnosis > 6months), stable hormone replacement therapy with glucocorticoids (no dose-adjustment >50mg hydrocortisone within the last 8 weeks) and mineralocorticoids (only primary adrenal insufficiency)! Or healthy control (no adrenal insufficiency, normal serum-electrolytes, normotensive blood pressure, no medication with a known influence on the electrolyte balance)! Exclusion Criteria: Pregnancy or breast-feeding Metal-implant (not MRI-compatible) Claustrophobia Chronic internistic disease (hypertension, heart failure, liver cirrhosis) Polydipsia (>4l/d) Long-term medication that can cause a hyponatraemia (for example diuretics)

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