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Question: What Are the Differences Between a Medical Laboratory Technician (MLT) and a Medical Laboratory Scientist (MLS)? (MLT vs. MLS)

Answer: Medical Laboratory Technician (MLT) and Medical Laboratory Scientist (MLS) are designations for clinical professionals who occupy different levels in the staffing hierarchy of medical laboratories. MLTs typically receive their training in two-year associate degree programs, while MLSs are generally required to hold a bachelor’s degree. MLSs, who may also be referred to Medical Technologists (MTs) or Clinical Laboratory Scientists (CLSs), are generally also required to attain a higher-level certification than MLTs from one of the three organizations that offer professional certifications in medical science: the American Society for Clinical Pathology (ASCP); the American Association of Bioanalysts (AAB); and the American Medical Technologists (AMT) association. In practical terms, MLSs are typically entrusted with a greater level of responsibility than MLTs and may be expected to work more autonomously than MLTs in most medical laboratory settings.

Medical laboratories are located in general medical and surgical hospitals and treatment centers and at independent laboratory facilities that service hospitals, clinics, and other healthcare facilities. These laboratories perform a range of diagnostic tests on biological specimens and are typically run under the direction of a medical doctor or team of physicians who have training in pathology, although research-oriented medical laboratories may instead be run under the direction of a chief scientist with a Ph.D. in medical science. Larger medical laboratories may have laboratory managers and/or pathology assistants who have master’s-level training in pathology, laboratory science, or laboratory management.

Much of the day-to-day testing in a medical laboratory is conducted by Medical Laboratory Scientists (MLSs), who may also be referred to as Medical Technologists (MTs) or Clinical Laboratory Scientists (CLSs), and by Medical Laboratory Technicians (MLTs), who occupy positions below MLSs in the medical laboratory staff hierarchy and are not tasked with the same level of responsibility as MLSs. For example, while MLTs and MLSs may both be entrusted to run various types of tests and handle biological samples, MLSs typically operate with greater autonomy and less supervision than MLTs and are generally qualified to conduct more complex testing procedures than MLTs.

Note: It is important to understand that there is variation in how medical laboratories are structured, in the specific responsibilities assigned to MLTs and MLSs, and in the professional designations given to MLTs and MLSs. Therefore, the information presented in this FAQ covers a general overview of how medical laboratories are typically staffed and not all medical laboratories follow the same organizational structures.

MLS vs. MLT: Training and Certification

MLSs typically hold a minimum of a bachelor’s degree and have specialized training through academic programs accredited by the National Accrediting Agency for Clinical Laboratory Sciences (NAACLS). There are NAACLS-accredited bachelor’s programs for MLSs, which require students to complete a year of clinical internships, and NAACLS-accredited post-baccalaureate certificate programs, which provide students who hold a bachelor’s degree in a field other than medical laboratory science with a pathway to become an MLS.

Graduates from NAACLS-accredited MLS programs who have a minimum of one year of full-time work experience in a medical laboratory are then eligible to apply for MLS certification through the American Society for Clinical Pathology (ASCP), or the MT certifications offered by the American Association of Bioanalysts (AAB) and American Medical Technologists (AMT) association.

In contrast to MLSs, MLTs typically receive their training in NAACLS-accredited associate degree programs, which typically take roughly two years or half the time required to complete bachelor’s-level training in medical laboratory science. MLTs receive professional credentials from the same three organizations that offer MLS/MT certifications once they have graduated from an MLT training program and completed a minimum of six months of laboratory experience.

The table below highlights some of the key differences between MLTs and MLSs:

Professional DesignationMLTMLS
Degree Level Typically RequiredAssociate DegreeBaccalaureate Degree
Laboratory ExperienceSix monthsOne year
Years of Academic and Professional TrainingTwo or three yearsFour or five years
CertificationsMLT (ASCP)

Note: While most states do not require medical laboratory personnel to be licensed, there are 11 states that require licensure for MLSs and MLTs. Licensing requirements vary by state, but the states that require licensure typically align their requirements with those established by the ASCP, AMT, and the AAB. The states that currently require licensure for MLTs and MLSs are: California, Florida, Georgia, Hawaii, Louisiana, Montana, Nevada, New York, North Dakota, Tennessee, and West Virginia. Puerto Rico also requires medical laboratory personnel to obtain a license.

MLT-to-MLS Articulation and Bachelor’s Completion Programs

MLTs who hold an associate’s degree from NAACLS-accredited programs are typically eligible to enroll in NAACLS-accredited bachelor’s programs designed to provide MLTs with a pathway to become MLSs without having to repeat courses common to both degrees. This process, which is described by the American Society for Clinical Laboratory Science (ASCLS) as MLT-to-MLS articulation, allows MLTs who have at least one year of laboratory experience to earn their bachelor’s degree and qualify for MLS/MT licensure in two years instead of the four or five years it typically takes to complete a full MLS bachelor’s program curriculum. (The ASCLS is a professional organization that supports and advocates for CLS practitioners, while also setting industry standards through its Code of Ethics, continuing education, annual meetings, and more.)

For more information on these types of programs, which are often designated as MLT-to-MLS Bachelor’s Completion Programs, refer to our Online Bachelor’s in Medical Laboratory Science (MLT-to-MLS) Degree Completion Programs page.

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