Endocrine Abstracts

Diabetes insipidus is a disease characterized by the inability to concentrate urine. The common form is central diabetes insipidus (CDI) caused by a lack of AVP after destruction of supraoptic–paraventricular nuclei. Further investigations are needed to establish its cause.: Case report

A 38-year-old woman presented with prompt polyuria–polydipsia. She has been taking contraceptive tablets for 2 years, smoked four to five cigarettes per day.

Blood test dismissed osmotic polyuria, so she was admitted into hospital to carry a water deprivation test (compatible with CDI).

She stopped contraceptive therapy and despite normal pituitary study, amenorrhea persisted (FSH 5.26 μU/ml, LH 2.59 μU/ml, estradiol 15 pg/ml, and prolactin 7 ng/ml). Hormone replacement therapy was started.

Pituitary RMI showed partial agenesia of corpus callosum and microadenoma of 7 mm. CBC, plasmatic calcium, α-fetoprotein and βhcg were normal. LDH 193.00 IU/l and antipituitary antibodies negatives.

18 months after diagnosis she was referred with dyspnea. Radiography showed reticular infiltrates in upper lung lobes; normal respiratory tests. HR-CT evidenced 2 cm bilateral lung cysts on superior-media lobes. Normal bronchoscopy and BAL. Transbronchial biopsy inconclusive thoracoscopy and biopsy showed fibrosis with lymphocytic infiltrates (strange body reaction). No treatments were indicated but stop smoking.

Two years later she appeared with disturbance thyroid axis (TSH 0.87 μIU/ml, T₄ 0.6 ng/dl) treated with levothyroxine 100 μg/day and also low IGF1 (71 ng/ml, age range 120–307), she initiated growth hormone replacement.

Additional tests ACE, ANA, ANCA, rheumatoid factor, protein account, abdominal ultrasound and bone map were all normal. PET–CT: lung parenchyma honeycombing.

Conclusion: Although she was initially diagnosed as idiopathic CDI, further studies made necessary differential diagnosis with other systemic diseases.

According to radiographic pattern and pituitary disease, etiologies to be considered are histiocytosis X (during scar phase, Langerhans cells may disappear in biopsy) and sarcoidosis (less likely).