There was no significant difference between the TPO-negative vs TPO-positive primary hypothyroidism groups in sex distribution (8 of 11 [73%] vs 6 of 9 [67%], P = .44), tyrosine levels (median, 1.14 [IQR, 0.91-1.23] mg/dL vs median, 5.02 [IQR, 1.41-8.77] mg/dL; P = .61), or urine HGA levels (median, 2044 [IQR, 988-2865] mmol/mol Cr vs median, 1732 [IQR, 1481-2967] mmol/mol Cr; P = .95) (Table 3). This evidence concerns the gene TPO and Primary hypothyroidism.