My son is 4 months 12lb. he's been sleeping through the night for the last 2 weeks. his diaper was orange tinted this morning. what does this mean?

Brick dust?: Urate crystals (commonly called "brick dust") are a combo of calcium and urate, substances normally found in urine. Crystals of the substance often form, leaving a red-orange stain in the diaper. More likely if baby is a little dehydrated or urine is very concentrated. Make sure he is getting enough feeds during the day and if it continues, talk to your sons doctor.