Jodid 100: composition and presentation
Jodid 100 comes as tablets containing either 100 µg or 200 µg of iodine in the form of potassium iodide. The figure in the name refers to the smaller of the two. It is worth noting how the content is expressed: it is given as pure iodine, while in the tablet the element is present as a salt, potassium iodide, which is why figures on packs from different manufacturers are sometimes compared wrongly. The unit here is the microgram, not the milligram, and that is no trifle: the difference between a preventive dose and a dose capable of harming the thyroid fits into a few hundred micrograms.
The tablet is taken after meals with a sufficient amount of liquid, roughly half a glass of water. The formulation contains lactose, so the medicine is not given to patients with the rare hereditary galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption syndrome. Iodine has no effect on the ability to drive or to operate machinery.
How Jodid 100 works
An adequate supply of iodine is essential for the body's own synthesis of thyroid hormones and for the normal structure and working of the gland itself. According to World Health Organization guidance an adult needs 150 to 300 µg of iodine a day — and those recommendations, as the description notes, have still not been met. An inadequate supply of iodine is a potential cause of disease: endemic goitre and, in severe cases, congenital cretinism.
From there the chemistry begins, and it explains why nothing can replace iodine. The epithelial cells of the thyroid follicles take up iodine electrochemically — a process called saturation, and it is what makes the thyroid the only organ that deliberately accumulates this element. Then, with hydrogen peroxide as a cosubstrate, oxidation takes place, assisted by iodide peroxidase, and organic iodine is formed. In the course of it some of the tyrosine residues of the glycoprotein called thyroglobulin become iodinated at position 3 and partly at position 5 of the aromatic ring. It is from those iodinated residues that thyroid hormones are later assembled, so without iodine coming in from outside the whole chain breaks at the first step.
Indications
There are three indications and all of them turn on iodine deficiency. The first is prevention of goitre in conditions of iodine deficiency, especially during pregnancy and breastfeeding. The second is preventing goitre from returning after treatment with thyroid hormones ends or after surgical removal of a goitre caused by iodine deficiency. The third is treatment of iodine-deficiency goitre in newborns, children and adolescents.
The difference between prevention and treatment is not a formal one here. A goitre is the enlargement with which the thyroid answers a shortage of raw material: receiving no iodine, the gland grows, trying to squeeze more hormone out of what it has. At an early stage restoring iodine brings it back to normal, which is why in children and adolescents iodine-deficiency goitre is actually treated. To an adult the medicine is more often prescribed so that a goitre does not appear at all, or does not return after surgery. The second indication deserves separate attention: after a goitre is removed or a course of thyroid hormones ends, the cause that led to the goitre has not gone anywhere, and without iodine the gland will start enlarging again — surgery removes the consequence, not the deficiency.
Method of use and dosage
Unless the doctor advises otherwise, the schedules below are followed. All doses are daily and expressed as pure iodine, so it follows directly from them which pack is needed: 100 µg or 200 µg. In setting the dose, regional and individual differences in iodine intake from food are taken into account — in some areas the water and produce contain more of it, in others almost none. This matters especially in newborns, infants and children up to four, whose own stores are small while their requirement per kilogram of body weight is, on the contrary, large.
| Situation | For whom | Daily iodine dose |
| Prevention of goitre in iodine deficiency | infants and children | 50–100 µg |
| The same | adolescents and adults | 100–200 µg |
| The same | pregnancy and breastfeeding | 200 µg |
| Preventing recurrence of goitre after hormone treatment or after surgery | all ages | 100–200 µg |
| Treatment of iodine-deficiency goitre | newborns and children | 100–200 µg |
| The same | adolescents | 200 µg |
The length of treatment differs even more than the dose. Preventive administration of iodide tablets usually has to continue for many years and often for life — the iodine deficiency of a region does not go away. Treating iodine-deficiency goitre in a newborn usually takes 2 to 4 weeks. Children and adolescents as a rule need iodine for 6 to 12 months, and sometimes longer.
Contraindications
The first contraindication is overt hyperthyroidism, that is, an already diagnosed overactivity of the thyroid. The second is worded unusually, with a dose attached: latent hyperthyroidism is a contraindication at iodine doses above 150 µg a day. In other words, for one and the same person 100 µg is permissible and 200 µg is not.
The third contraindication is an autonomous thyroid adenoma, as well as focal or diffuse nodular goitre with autonomous secretion. The word "autonomous" is the key one: normally the gland releases hormones on the pituitary's command, but a nodule or an adenoma can work on their own, outside that regulation. Such tissue does not care how much hormone is already in the blood: given an excess of iodine it will simply produce more, and hyperthyroidism will follow. The list closes with hypersensitivity to the active substance or to any excipient.
Special warnings and precautions
Before the medicine is used it must be established that the patient neither has now nor has had in the past hyperthyroidism or nodular goitre. Before iodine treatment begins, appropriate diagnostic work is done to rule out diffuse or focal autonomous secretion of thyroid hormones: where it is present, iodine doses above 150 µg a day are capable of causing hyperthyroidism. That is the governing rule of this page — iodine is harmless only to a gland that is regulated normally. Exactly what diagnostic work is needed the description does not specify: that is for the doctor to decide, given the age, the complaints and what is already known about the gland. The point of the check is to tell a thyroid working evenly from one with areas that have escaped the pituitary's control.
The second point concerns radioactive iodine. Saturating the thyroid with iodine may prevent the optimal accumulation of radioactive iodine given for diagnostic or therapeutic purposes, so before such procedures the medicine must be stopped in good time. The logic is simple: a gland already filled with ordinary iodine will not take up the labelled kind, and the investigation or the treatment will lose its point. The patient does well to remember this too — a referral for a scan or for radioiodine therapy is issued weeks before the procedure itself, and the tablets should be mentioned straight away.
Interactions with other medicines
The relations between iodine and thyroid treatment are mutual and work both ways. Iodine deficiency strengthens the response to antithyroid treatment in hyperthyroidism, while an excess of iodine weakens that response; for that reason every avoidable intake of iodine is stopped before treatment of hyperthyroidism and throughout its course. In the opposite direction work the antithyroid drugs themselves: they block the binding of iodine in the thyroid gland and so can act as goitrogenic factors.
The uptake of iodine by the thyroid is blocked competitively by substances with the same uptake mechanism — perchlorate, for instance, which also blocks the internal recycling of iodine — and by substances that are not transported, such as thiocyanate at concentrations above 5 mg per decilitre. Uptake and internal recycling of iodine are stimulated, by contrast, by the pituitary hormone TSH. Two combinations are named separately: large doses of iodine, which block hormone release from the gland, together with lithium raise the risk of goitre and hypothyroidism, and large doses of potassium iodide together with potassium-sparing diuretics may lead to hyperkalaemia.
Pregnancy and breastfeeding
In pregnancy and during breastfeeding the requirement for iodine rises, so an adequate supply of the element matters here especially — 200 µg a day. It is precisely this group that appears in the indications as well: prevention of goitre in iodine deficiency is called relevant above all for pregnant and breastfeeding women. Iodine crosses the placenta and passes into milk, and its concentration there is thirty times higher — the mother's body supplies the child with it deliberately.
Two practical conclusions follow. The first: in setting the dose, the iodine already coming in from dietary supplements must be counted, or it is easy to exceed the norm by adding the tablet to a vitamin preparation. The second: a breastfed newborn needs no additional iodine supplement, receiving it with the milk. At the same time, because of the great sensitivity of the foetal and neonatal thyroid, very large doses of iodine — of the order of milligrams — should be avoided in pregnancy and while breastfeeding. One exception is set out separately: preventive blockade of the thyroid with large doses of iodine after nuclear accidents.
Adverse reactions
The adverse reactions section is short for this medicine, and both situations described have to do not with iodine itself but with the state of the thyroid receiving it. The first: if there are large foci of autonomous secretion in the gland, the emergence of hyperthyroidism at iodine doses above 150 µg a day cannot be entirely ruled out. That threshold recurs in the contraindications and in the warnings alike — in essence, the whole safety of the medicine rests on whether autonomy was excluded before it was started.
The second situation concerns people predisposed to autoimmune thyroid disease: in them antibodies to thyroid peroxidase may form, the very anti-TPO antibodies measured in tests. Their appearance does not in itself mean disease, but it calls for an endocrinologist's attention. Noticing either of these by how one feels is hard — hyperthyroidism may begin with irritability, palpitations, sweating and weight loss, and not everyone will connect them with a tiny iodine tablet.
Overdose
Acute overdose shows itself as brown staining of the mucous membranes, vomiting, abdominal pain and diarrhoea; dehydration and shock are possible, and in rare cases oesophageal stenosis has been seen. Deaths occurred only after extraordinarily large amounts of iodine were taken — 30 to 250 ml of iodine tincture — that is, in poisoning with quite different preparations, not with tablets measured in micrograms. Treatment of acute poisoning consists of gastric lavage, correction of water and electrolyte disturbances, treatment of shock and other symptomatic measures.
Chronic overdose leads to iodism, iodine poisoning. Its features are recognisable: a metallic taste in the mouth, a runny nose, conjunctivitis, irritation of the gastric and bronchial mucosa, skin changes — blisters, thickening, peeling — and angioedema; very rarely fever, acne and increased salivation have been described. In chronic overdose iodine is stopped. If iodine has caused hypothyroidism, it is withdrawn and thyroid hormones given. Iodine-induced hyperthyroidism is treated with antithyroid drugs, and in very severe cases an intensive care unit, plasmapheresis and sometimes even removal of the thyroid are needed.
How to get a Jodid 100 prescription online
That the medicine requires a prescription often comes as a surprise: iodine is, after all, sold as a dietary supplement too. The difference lies in the dose and in the purpose — the tablet is prescribed for a specific state of the thyroid, not "for prevention in general". At e-zdrowie.com the prescription is arranged remotely: a questionnaire, the doctor's review of the answers, and an electronic prescription as a code in a message, against which any Polish pharmacy will dispense the tablets. Treatment here runs for years and the dose, once set, does not change, so the format fits renewals particularly well.
The main thing the questionnaire has to establish is the state of the thyroid. State whether it has ever been examined, whether an ultrasound was done and whether nodules were found, whether TSH was measured and when, whether there has been hyperthyroidism, an adenoma or nodular goitre, whether the gland was removed and whether hormone treatment was given. Be sure to report pregnancy or breastfeeding, the use of lithium, potassium-sparing diuretics and antithyroid drugs, and also any iodine-containing supplements and vitamins — their dose is added to that of the tablet. And say separately if an investigation or treatment with radioactive iodine is planned: the medicine will have to be stopped well before it.
