Table 2.

Parameters of the biokinetic model for iodine in pregnancy for the carrier-mediated processes (for the structure, see Figs. 1 and 2)

		Pregnancy week
		0	3	8	12	16	24	32	36	38
		Mother
Blood to thyroid iodide	k	2.3	2.3	2.3	2.3	2.3	2.3	2.3	2.3	2.3
	Km	63	63	63	63	63	63	63	63	63
	Tmax	144.9	144.9	144.9	144.9	144.9	144.9	144.9	144.9	144.9
Blood to thyroid organic iodine	k	2.3	5.1	6.5	7.5	8.4	9.3	9.1	8.8	8.7
	Km	63	63	63	63	63	63	63	63	63
	Tmax	144.9	321.3	409.5	472.5	529.2	585.9	573.3	554.4	548.1
Blood to salivary gland	k	3.0	3.0	3.0	3.0	3.0	3.0	3.0	3.0	3.0
	Km	63	63	63	63	63	63	63	63	63
	Tmax	189	189	189	189	189	189	189	189	189
Blood to gastric secretory cells	k	8.6	8.6	8.6	8.6	8.6	8.6	8.6	8.6	8.6
	Km	63	63	63	63	63	63	63	63	63
	Tmax	541.8	541.8	541.8	541.8	541.8	541.8	541.8	541.8	541.8
Blood to placenta iodide	k	0	0	33	33	33	33	33	33	33
	Km	–	–	63	63	63	63	63	63	63
	Tmax	–	–	2079	2079	2079	2079	2079	2079	2079
		Fetus
Fetal iodide to fetal thyroid	k	0	0	0	1.8	3.5	5.0	6.0	6.0	6.0
	Km	–	–	–	0.405	0.999	4.059	10.404	14.337	16.2765
	Tmax	–	–	–	0.729	3.4965	20.295	62.424	86.022	97.659

The first-order kinetic rate constants (k in d⁻¹) are from the Berkovski (2002) model. In our new model, the carrier-mediated transport processes are described by Michaelis–Menten kinetics with two parameters: the Michaelis–Menten constant (K_m) expressed in µmol d⁻¹ instead of concentration (µmol l⁻¹) as we use iodine amounts (µmol) in our computations; T_max (µmol d⁻¹): the maximum transport capacity of the process. For the derivation of K_m et T_max from the rate constants k and the volumes of distribution (Table 1), see the Method section