Lack of accessible medical care in developing countries has prompted a need for low-cost point of care medical diagnostics. Paper based medical diagnostics have been demonstrated as a viable option in these areas due for their simplicity, low-cost and easy disposal. This paper presents a custom CMOS readout IC in conjunction with paper-based electrodes as electrochemical sensors as a low-cost medical diagnostics platform. The CMOS readout IC consists of a drive amplifier and a VLSI potentiostat made from class AB buffer-amplifiers for electrochemical sensing. To demonstrate system functionality, the readout IC and fabricated paper-electrodes are used for the sensing of dopamine, a neurotransmitter also found in both blood and urine and is an early indicator of multiple medical disorders.