Right painful hip in Gitelman's syndrome

Clinical History

A 33-year-old female patient with known Gitelman’s syndrome, presented with a 6-month right painful hip area.

Imaging Findings

MR imaging of the hip joints, showed a minimal avascular necrosis (AVN) lesion on the left femoral head, a large AVN lesion on the right, extensive bone marrow oedema on the right and joint effusion. The high resolution T2* image showed early articular collapse, demonstrated with mild flatterning and loss of sphericity, of the right femoral head, which is associated with the bone marrow oedema and suggests advanced stage. The fat suppressed contrast enhanced images also showed reactive synovitis.

Discussion

A. Gitelman's syndrome (GS) is a rare autosomal recessive, inherited renal tubular disorder that is characterized by hypokalemia, metabolic alkalosis, hypomagnesemia and hypocalciuria [1].
GS is commonly caused by a mutation in the SLC12A3 gene on chromosome 16q13 which encodes the thiazide-sensitive cotransporter (TSC), also called the Na-Cl cotransporter (NCCT), in the distal convoluted tubule [1, 2].
Decreased absorption in the distal convoluted tubule results in more sodium delivered to the collection duct, causing a mild volume contraction and stimulating the renin-angiotensin-aldosterone system. Increased aldosterone levels increase sodium resorption in the collecting ducts and urinary secretion of potassium and hydrogen ions [2].

B. The clinical manifestations of GS most often appear during the adolescent or the early adult years. They are usually very mild, with the most common being salt craving, musculoskeletal disorders like cramps, carpopedal spasms, paraesthesiae, weakness and aches and constitutional problems like fatigue, dizziness, nocturia and polydipsia [1, 3]. More severe symptoms, like tetany, rhabdomyolysis, paralysis and heart dysrhythmias like ventricular tachycardia and even syncopy and sudden cardiac death have been reported [3]. As the GS is not associated with typical imaging findings, MRI was suggested for exploring the painful hip.

C. A simple X-ray may demonstrate marked chondrocalcinosis in GS patients [4]. MRI showed findings consisted with AVN (Fig.1-6). Plain radiographs are normal in the early stages of AVN (ARCO stage I). MRI is the method of choice showing the pathognomonic low signal intensity "band-like" sign [5]. In stages II and III, radiographs show serpentine like suchnondral osteosclerotic line and "crescent" sign respectively [5]. Bone marrow edema on MRI suggests advanced disease with articular collapse [6]. Contrast enhanced images show to better advantage the presence of synovitis and the articular surface flattening due to inherent high signal to noise ratio that T1-w images provide allowing acquisition of thinner slices. Our patient showed mild collapse (Fig. 4) and bone marrow edema (Fig. 1-3, 5, 6) in keeping with ARCO stage IIIA .

D. AVN with early collapse can be treated either with weight bearing protection until clinical improvement or with peroneal vascularized grafting as a joint preserving procedure [5].

E. No typical imaging findings exist in GS. Painful hip in young adults may result from transient osteoporosis of the hip, AVN, and impingement syndromes. Careful clinical examination and prompt use of MRI will allow accurate and early diagnosis of AVN contributing thus to a joint preserving treatment planning.

Differential Diagnosis List

Final Diagnosis

Avascular necrosis of the hip in a patient with GS

URL:	https://eurorad.org/case/14079
DOI:	10.1594/EURORAD/CASE.14079
ISSN:	1563-4086