An interesting case of Diabetes Insipidus.
Morris LA, Smith P.
A 37 year old gentleman was referred to the endocrinology clinic with a three month history of profound polydipsia and polyuria, coupled with loss of muscle bulk without weight loss. He reported an intake of 9-11 litres of water daily. His medical history included a head injury following a road traffic accident and left retro-orbital tumour excision by maxillofacial surgeons in Liverpool two years earlier. A water deprivation test was arranged. High urine output was observed (600 – 700ml per hour) and body weight reduced by 5% within 4-5 hours. After DDAVP, urine concentration increased from 148mOsmol/kg to 500 mOsmol/kg. A diagnosis of cranial diabetes insipidus (CDI) was made. He responded well to treatment with oral desmopressin.
Additional tests to evaluate pituitary function revealed hypogonadotrophic hypogonadism - FSH 0.8 IU/l, LH 107 IU/l, testosterone 5.4nmol/l; normal prolactin 215 mU/l, and thyroid function TSH 1.56 mU/l, FT4 9pmol/l. The patient was commenced on intra-muscular testosterone therapy. An insulin stress test demonstrated a normal cortisol (basal 213nmol/l, peak 541nmol/l) but inadequate growth hormone (basal GH 0.16 ug/l peak 0.84 ug/l) response to hypoglycaemia. A pituitary MRI revealed diffuse infiltrative change within the posterior pituitary suggestive of granulomatous change or histiocytosis. Pathology review in Liverpool of the retro-orbital tumour led to the diagnosis being revised from a mixed cellular infiltrate to Langerhans Cell histiocytosis (LCH).
Between presentation and diagnosis of CDI the patient developed an itchy, papular, nodular rash over his scalp. A skin biopsy showed features compatible with LCH. It was concluded that this gentleman had systemic LCH with pituitary, retro-orbital and dermal involvement. The rarity and progressive nature of LCH prompted a referral to a multidisciplinary LCH clinic at the Hammersmith Hospital. Further investigation with CT and isotope bone scanning revealed bony involvement within the sternum. He was commenced on oral methotrexate and within two months the scalp lesions had shown considerable regression.
Despite good control of the CDI, adequate testosterone replacement and resolution of skin disease, the patient continues to complain of fatigue and is keen to commence growth hormone replacement. It is however less than a year since diagnosis and commencement of treatment. The endocrine team are uncertain as to whether growth hormone therapy may have an adverse effect on LCH disease activity. A review of the literature suggests that growth hormone replacement does not reactivate LCH in children with systemic disease and established growth failure 1,2, but it is not made clear whether the subjects had active LCH when treatment was commenced.
This gentleman’s diagnosis and management has required expert input across multiple specialties, including endocrinology, maxillofacial surgery, pathology, radiology and dermatology in three different hospitals. A multidisciplinary approach has facilitated a prompt diagnosis and effective treatment.
1Nanduri VR, Bareille P, Pritchard, J, Stanhope R. (2000). Growth and endocrine disorders in multisystem Langerhan’s cell histiocytosis. Clinical Endocrinology. 53. 509-515.
2Howell, S.J., Wilton, P. & Shalet, S.M. (1998) Growth hormone replacement in patients with Langerhans' cell histiocytosis. Archives of Disease in Childhood. 78, 469-473.