Backgrond: The thyroid is a hormone-producing endocrine gland which is located in the front of the throat. The thyroid gland tissue contains several microscopic and spherical cavities called follicles. Thyroid hormones thyroxine (T4) and triiodothyronine (T3) are produced from the follicle cells and regulated by a so-called three-hormone sequence. Thyroid stimulating hormone (TSH) is the second hormone in the sequence and is produced from the pituitary gland. During pregnancy, the thyroid gland produces a greater amount of hormone to cater the needs of the mother and her offspring. When the gland produces too little hormone, it is called hypothyroidism. The disease causes symptoms such as chills, dryness, depression, and hair loss. The disease is divided into different types depending on the underlying cause of the disease. It is called primary hypothyroidism when disorders are in the thyroid gland itself and secondary when the problem is elsewhere in the body, usually in the hypothalamus. Hypothyroidism during pregnancy increases the risk of obstetric complications and can also lead to reduced IQ development in the fetus. Levothyroxine is a synthetic T4 and is used as a first-line drug in the treatment of hypothyroidism. Aim: The aim of this study was to investigate whether treatment with levothyroxine in subclinical hypothyroidism in pregnancy reduces the risk of pregnancy complications and also to analyze how thyroid autoimmunity and subclinical hypothyroidism affect the pregnant woman. Method: The work is a literature study conducted using six relevant published articles retrieved from the medical database and the search engine PubMed. Results: The studies 2,4,5 concluded that subclinical hypothyroidism and thyroid autoimmunity increase the risk of pregnancy complications. Studies 1 and 6 could not show any connection between these groups. Levothyroxine treatment in pregnancy with TSH value greater than 4 mIU/L is effective and leads to reduced risk of miscarriage, admission to neonatal wards and premature birth. In addition, the studies showed that the levothyroxine treatment in patients with TSH value less than 4mIU/L is without any significant effect.   Conclusion: The evidence at present, is unclear and there is insufficient data to determine the efficacy of treatment in patients with TSH levels below 2.5 mIU / L. More and larger clinical randomized controlled trials in pregnant women with subclinical hypothyroidism and positive for thyroperoxidase antibodies are needed to increase the validity of the treatment. In contrast, levothyroxine treatment in mothers with a TSH level in serum greater than 4 mIU / L is effective and of significant importance for both the woman and her offspring.

Syftet med det här arbetet var att undersöka en eventuell koppling mellan subklinisk hypotyreos och depression. De hypoteser som prövas är: ”Värdet för tyreoideastimulerande hormon (TSH) kan användas som markör för depression” samt ”Värdet för antikroppar mot tyreoperoxidas (TPOAk) kan användas som markör för depression”. Metoden som använts är en litteraturstudie. Vetenskapliga artiklar publicerade 2012 och framåt som möter inklusionkriterierna har använts. Dessa kriterier var att artiklarna skulle vara orginalstudier, vetenskapligt granskade, mäta nivåer av TSH och TPOAk i serum samt undersöka sambandet mellan hypotyreos och depression genom att titta på serumnivåer av TSH och TPOAk. Studierna skulle ej vara utförda på djur. Resultatet visar att fyra av sju artiklar påvisar ett positivt samband mellan hypotyreos och depression. Det visar även att tre artiklar kunde påvisa ett positivt samband mellan TSH och depression och tre artiklar kunde påvisa ett positivt samband mellan TPOAk och depression. Slutsatsen är att det verkar finnas ett samband mellan subklinisk hypotyreos och depression samt att TSH och TPOAk inte enskilt utgör markörer för depression men det sammantagna värdet av dem bör kunna ge en indikation på om det finns ett samband eller inte. / The aim of this study was to investigate a possible link between subclinical hypothyroidism and depression. The hypotheses that where being tested are: "the level of thyroid stimulating hormone (TSH) can be used as a marker for depression" and "the level of thyroperoxidase antibodies (TPOAb) can be used as a marker for depression". The method used is a literature review. Scientific articles published in 2012 and forward meeting the criteria for inclusion have been used. These criteria were that the articles would be original, peer-reviewed studies, measuring levels of TSH and TPOAb in serum and examine the link between hypothyroidism and depression by looking at serum levels of TSH and TPOAb. The studies should not be conducted on animals. The results show that four out of seven articles indicate a positive association between hypothyroidism and depression. It also shows that three articles were able to demonstrate a positive association between the TSH and depression and three articles were able to demonstrate a positive association between TPOAb and depression. The conclusion is that there appears to be a link between subclinical hypothyroidism and depression and that the levels of TSH and of TPOAb do not individually represent markers of depression but the overall value of them should be able to give an indication of whether there is a connection or not.