Volume 70, Issue 10, December 2023, Pages 649-653Author links open overlay panel, , , , , , Abstract

A 45-year-old woman suffering from primary hypothyroidism, previously well substituted with levothyroxine, was urgently referred from Primary Care to Endocrinology due to very elevated thyrotropin, free thyroxine at low limit of normality, very high cholesterol and generalised oedema. Hypothyroidism was suspected as the main aetiology of this clinical condition. A detailed examination showed nephrotic range proteinuria and the patient was finally diagnosed with lupus nephritis. Urinary loss of thyroid hormones, fundamentally linked to their transport proteins, in patients affected by nephrotic syndrome is sometimes a forgotten phenomenon and one which should be considered in patients with increased levothyroxine requirements. In this report, we present the details of this case and a brief review of the literature on this topic.

Resumen

Mujer de 45 años con hipotiroidismo primario, previamente bien sustituido con levotiroxina, remitida de urgencia desde Atención Primaria a Endocrinología por tirotropina muy elevada, tiroxina libre en límite bajo de la normalidad, colesterol muy elevado y edema generalizado. Se sospechó hipotiroidismo como principal etiología de este cuadro clínico. Un examen detallado mostró proteinuria de rango nefrótico y la paciente fue finalmente diagnosticada de nefritis lúpica. La pérdida urinaria de hormonas tiroideas, ligada fundamentalmente a sus proteínas transportadoras, en pacientes afectos de síndrome nefrótico es a veces un fenómeno olvidado y que debe tenerse en cuenta en pacientes con requerimientos elevados de levotiroxina. En este artículo presentamos los detalles de este caso y una breve revisión de la literatura sobre este tema.

Section snippetsCase description

A 42-year-old woman consulted for symptoms of asthenia, poorly quantified weight loss, diarrhoea and palpitations, with a five-month history. She also complained of itchy eyes and swollen eyelids. As a previous medical history, she presented penicillin allergy, she was a smoker of 10 cigarettes/day and she had suffered from epilepsy since childhood, which remained stable and without crisis in recent years. She was not taking any pharmacological treatment. Physical examination showed a diffuse

Management

On physical examination, there was certainly a generalised tension oedema in both lower extremities. The patient was moderately hypertensive (blood pressure 153/82 mmHg). Cardiorespiratory status was good, without significant abnormalities in auscultation and with an oxygen saturation of 99%. Based on the significant oedema and severe hypercholesterolaemia, not justifiable due to the degree of hypothyroidism she showed, the possibility of nephrotic-range proteinuria was suspected. A

Areas of uncertainty

This case is a good illustration of the relationship that may exist between the presence of proteinuria and changes in thyroid hormones. Although an increase in levothyroxine requirement may have a multifactorial origin (increased body weight due to oedema, reduced absorption due to intestinal wall oedema) we think that a fundamental element was urinary loss of thyroid hormone binding proteins and, regarding this phenomenon, we decided to do a brief review of the scientific literature on this

Discussion

Relationship between thyroid and kidney physiology is very important and increasingly well known. Normality of thyroid hormones is necessary for embryonic development of kidney and thyroid hormones influence the activity of many co-transporters of kidney tubules and regulate glomerular haemodynamics. Thus, it is well established that hypothyroidism leads to a decrease in GFR and an impaired ability to excrete free water. In contrast, hyperthyroidism implies an increase in GFR with decreased

Conclusions and recommendations

Urinary loss of thyroid hormones, fundamentally linked to their transport proteins, is a phenomenon that must be considered in patients with nephrotic-range proteinuria. In patients with prior hypothyroidism, it will increase levothyroxine requirement and in subjects without prior hypothyroidism it may trigger its occurrence.

Measurement of thyroid hormones should be recommended in patients with nephrotic syndrome, as well as assessing the presence of proteinuria in subjects affected by

Funding

This article is a clinical case with a review of the literature. It has not had any specific funding.

Conflict of interests

The authors declare that they have no conflict of interest.

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