The Netherlands Journal of Medicine
Brief reportHyponatremia due to hypothyroidism: a pure renal mechanism
Introduction
Hyponatremia is an important clinical problem. The prevalence of hyponatremia (Na<131 mmol/l) in patients admitted to the Department of Internal Medicine is 1.25% [1]. The prevalence of hyponatremia in all the hospital departments is 0.97% and in the department of Surgery the prevalence is even higher: 4.4% [2], [3]. In the hospital laboratory hyponatremia (Na<137 mmol/l) occurs in 23.4% of all serum sodium assays (Na 130–137 mmol/l in 20.4%; Na 120–129 mmol/l in 2.7%) [4].
Hyponatremia may cause life-threatening clinical symptoms like seizures, coma, respiratory arrest and brain-stem herniation that need to be treated according to its pathophysiology and taking into account the rate of development [5]. It can be a symptom of an important underlying, but not yet identified, disease. In every case of hyponatremia a careful diagnostic analysis must be performed. Only after understanding its pathophysiology treatment can be installed appropriately. We describe a patient in whom initially several possible causes of hyponatremia were considered. Eventually an uncommon, but — in this particular patient — not unexpected, diagnosis could be made.
Section snippets
Case report
An 88-year-old man was admitted to the otorhinolaryngology department of our hospital because of leakage of a speaking valve. The patient’s medical history included a pT4N0M0 hypopharynxcarcinoma 3 years earlier that was treated by laryngectomy, partial hypopharyngectomy, hemithyroidectomy, right-sided cervical lymph node dissection and radiotherapy. One month before admission he was treated with paroxetine by his general practitioner because of a depression. He did not use any other drugs. On
Discussion
Hyponatremia is defined as a decrease in the serum sodium concentration below 135 mmol/l. The serum sodium concentration is the main determinant of the plasmaosmolality.
As a result hyponatremia usually reflects hypoosmolality. Hypotonic hyponatremia represents an excess of water in relation to existing sodium stores, which can be decreased, normal or increased. The primary response to a fall in plasmaosmolality, as occurs in normal subjects after the ingestion of a water load, is to diminish
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2013, Medical Journal Armed Forces IndiaCitation Excerpt :This can directly diminish free water excretion by diminishing water delivery to the diluting segments. Decreased delivery may be particularly important in those cases in which hyponatremia develop despite appropriate suppression of ADH release.11 The incidence detected in our study is comparable to various other studies.
Vasopressin, Diabetes Insipidus, and the Syndrome of Inappropriate Antidiuretic Hormone Secretion
2010, Endocrinology: Adult and Pediatric, Sixth EditionChronic Thyroiditis
2009, Clinical Management of Thyroid DiseaseDisorders of Body Water Homeostasis in Critical Illness
2006, Endocrinology and Metabolism Clinics of North AmericaCitation Excerpt :Moreover, once thyroid hormone replacement was given and thyroid function normalized, creatinine values returned to their baseline euthyroid levels before the iatrogenically induced hypothyroid state [47]. Based on this combined evidence, the major cause of impaired water excretion in hypothyroidism appears to be an alteration in renal perfusion and GFR secondary to systemic effects of thyroid hormone deficiency on cardiac output and peripheral vascular resistance [48–50]. In hypervolemic hyponatremia, there is an excess in total body water and total body sodium, resulting in clinically evident edema or ascites; however, in many cases, the increase in total body water is out of proportion to that of total body sodium, causing hyponatremia.
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