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AN EXCEPTIONAL CASEOF SEVEREHYPOCALCEMIA F. SabbatiniGiulia LussignoliGiorgio Kuffenschin2006 год

AN EXCEPTIONAL CASE OF SEVERE HYPOCALCEMIA
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Аннотация: To the Editor: A 79-year-old woman was admitted to our Memory Clinic with a 20-day history of delirium associated with restlessness and upper limb tremor. She had been in good health until 4 years before, when she underwent thyroidectomy for cancer and L-thyroxine 100 μg daily was prescribed. On admission, the patient was awake, apathetic, and disoriented in time. Her gait was unsteady and slow, with a tendency to fall backward while standing with eyes closed. Neurological examination showed resting and action tremor, upper limb myoclonus, and increased muscle tone without strength deficit. Cranial nerves were normal. Release signs could not be elicited, but Chvostek's sign was present. Neuropsychological examination showed severe attentional disturbances and deficits in long- and short-term episodic and visuospatial memory, acalculia, and poor word production, although autobiographic memory was preserved. Mini-Mental State Examination (MMSE) score was 13 of 30. Blood tests revealed severe hypocalcemia (3.8 mg/dL) associated with hyperphosphatemia (6.9 mg/dL) and low serum parathormone levels (4.0 pg/mL). Brain computed tomography scan was normal, except for small ischemic lesions in both internal capsules. An electrocardiogram revealed prolonged QT interval without rhythm abnormalities. During hospitalization, calcium and cholecalciferol supplementation led to progressive recovery. Neuromuscular symptoms gradually disappeared, and upon discharge, 18 days after admission, the patient was oriented to time and space and cognitively intact. Six months later, she scored 30 of 30 on the MMSE, and neuropsychological tests were also normal. The rapid onset of the cognitive impairment, its characteristics, and the clinical and laboratory findings supported a diagnosis of delirium due to hypocalcemia. Cognitive changes related to hypocalcemia have been reported in three cases of dementia in patients with idiopathic hypoparathyroidism.1–3 Reversible dementia that was attributed to hypoparathyroidism has also been described in a normocalcemic patient.4 The relevance of the current case is mainly due to the scanty clinical findings despite very low calcium levels. In particular, the only typical sign was a mild prolongation of the QT interval on electrocardiogram, whereas tetany, which usually appears when ionized calcium concentrations fall below 4.3 mg/dL (corresponding to total calcium of 7.0 mg/dL), was absent. It was hypothesized that a physiological adaptation to chronic progressive hypoparathyroidism developed over 4 years, perhaps resulting from impairment of the vascular supply of the parathyroid glands, secondary to fibrotic changes of the neck after thyroidectomy, could have explained this. It was not possible to identify the trigger event that might have upset the homeostatic balance that led to delirium. After thyroidectomy, the patient failed to undergo adequate follow-up, and hypocalcemia, a potentially fatal complication, was discovered thanks only to the sudden onset of cognitive and functional impairment. The paucity of symptoms and the rapid recovery indicate that the patient was not frail and had preserved homeostatic reserves. Alternatively, the development of delirium as the main clinical manifestation of hypocalcemia underlines the greater vulnerability of the central nervous system than that of other organ systems, confirming the relevance of delirium as a marker of quality of medical care in older people.5 Financial Disclosure: None of the authors has any direct or indirect conflicts related to this manuscript. Author Contributions: Federica Sabbatini participated in study concept and design, acquisition and interpretation of data, preparation of manuscript. Giulia Lussignoli participated in acquisition of data. Giorgio Kuffenschin participated in acquisition of data, mainly in follow-up. Cristina Geroldi participated in preparation of manuscript. Mirco Neri participated in interpretation of data and preparation of manuscript. Orazio Zanetti participated in study concept, interpretation of data, and preparation of manuscript. Sponsor's Role: No sponsor was involved in the design, methods, acquisition of data, or preparation of this letter.
Год издания: 2006
Авторы: F. Sabbatini, Giulia Lussignoli, Giorgio Kuffenschin, Cristina Geroldi, Mirco Neri, Orazio Zanetti
Издательство: Wiley
Источник: Journal of the American Geriatrics Society
Ключевые слова: Intensive Care Unit Cognitive Disorders, Thyroid and Parathyroid Surgery, Anesthesia and Sedative Agents
Другие ссылки: Journal of the American Geriatrics Society (PDF)
Journal of the American Geriatrics Society (HTML)
PubMed (HTML)