diff --git a/src/entity/reference_range.ts b/src/entity/reference_range.ts
index 56e7929..995d6e3 100644
--- a/src/entity/reference_range.ts
+++ b/src/entity/reference_range.ts
@@ -16,38 +16,30 @@ export class ReferenceRange {
 	gender: Gender;
 
 	@Column({
-		type: 'integer',
 		nullable: false,
-		default: 0,
-		comment: 'Age range minimum in days',
+		length: 128,
+		default: '0 day',
 	})
-	age_range_min: number;
+	age_range_min: string;
 
 	@Column({
-		type: 'integer',
 		nullable: false,
-		default: 36500,
-		comment: 'Age range maximum in days (36500 = ~100 years)',
+		length: 128,
+		default: '999 years',
 	})
-	age_range_max: number;
+	age_range_max: string;
 
 	@Column({
-		type: 'decimal',
-		precision: 10,
-		scale: 2,
 		nullable: false,
-		comment: 'Minimum reference value',
+		length: 256,
 	})
-	value_min: number;
+	value_min: string;
 
 	@Column({
-		type: 'decimal',
-		precision: 10,
-		scale: 2,
 		nullable: false,
-		comment: 'Maximum reference value',
+		length: 256,
 	})
-	value_max: number;
+	value_max: string;
 
 	@Column({
 		nullable: false,