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Timed and forensic collections

15 min

Skills you'll build2 skills
  • Recognize an incomplete or mistimed urine collection before calculation
  • Maintain chain of custody for a federal workplace urine specimen

At the bench: Check specimen identity and suitability before analysis

Try first

Try first

A patient starts a 24-hour urine at 07:00 by voiding into the collection container. He saves every void after that and ends at 07:00 the next day with a final void into the container. What does this do to the calculated daily excretion?

Keep going to see the reasoning.

Right. Keep going to follow the reasoning.

Keep going to see the reasoning.

Keep going to see the reasoning.

Get the idea

Use the explanation to check your first decision.

A timed collection needs every void and the exact interval

A 24-hour urine measures how much of an analyte the patient excreted in one day. The performing laboratory supplies the container, any preservative and the instructions before the start, because some analytes need a preservative from the first void.1

  1. At the start time, empty the bladder and discard that urine.
  2. Save every void for the next 24 hours.
  3. At the end time, empty the bladder and keep that urine.
  4. Mix the whole collection, measure and record the volume, then take the aliquot.1

Amount collected (mg) = urine concentration (mg/dL) × collection volume (mL) ÷ 100. Divide by collection duration (h) for mg/h. A full-day amount requires the specified complete collection or permitted time normalization. Every number in that calculation depends on the collection. A missed void makes excretion falsely low. A saved start void adds urine formed before the interval and makes it falsely high. The aliquot cannot show either error.1

Two findings suggest a missed void. A volume of about 700 mL is low for an adult who is not fluid-restricted. Total creatinine below the expected daily output, about 800 to 2,000 mg/day in men and 600 to 1,800 mg/day in women, suggests missing urine.1,2 Check the recorded times and ask about missed voids before looking for an analytical problem.

A forensic specimen travels with its custody record

Federal workplace urine drug testing uses the Federal Custody and Control Form (Federal CCF). It records every transfer of the specimen and the condition of the primary seal at receipt.3,4

  • The donor provides at least 45 mL. The collector pours at least 30 mL into bottle A and at least 15 mL into bottle B.
  • The collector reads the temperature within 4 minutes. Outside 32 to 38 °C (90 to 100 °F), a second collection under direct observation follows.
  • The donor watches the sealing, initials both seals and signs the donor certification. The collector completes the form and ships the package within 24 hours to a laboratory or instrumented initial test facility (IITF) certified by the Department of Health and Human Services (HHS).
  • At receipt, the certified facility records the date, the primary seal's condition and the specimen's release to storage.3,4

A nonfederal program follows its own written requirements, so confirm which program governs the specimen before handling it.5

Follow the bench demonstration

Sources for this step
References
  1. Clinical and Laboratory Standards Institute. Processes for the Collection of Urine Specimens. 1st ed. CLSI guideline PRE05. Clinical and Laboratory Standards Institute; 2024. Accessed September 27, 2026. https://clsi.org/shop/standards/pre05/
  2. Bishop ML, Fody EP, Van Siclen C, Mistler JM, Moy M. Clinical Chemistry: Principles, Techniques, and Correlations. 9th ed. Jones & Bartlett Learning; 2023.
  3. Substance Abuse and Mental Health Services Administration. Urine Specimen Collection Handbook for Federal Agency Workplace Drug Testing Programs. Effective February 1, 2024. Accessed September 27, 2026. https://www.samhsa.gov/sites/default/files/urine-collection-handbook-2024.pdf
  4. Substance Abuse and Mental Health Services Administration. Guidance for Using the 2026 Federal Custody and Control Form (CCF). Published April 29, 2026. Accessed September 27, 2026. https://www.samhsa.gov/sites/default/files/guidance-using-2026-federal-custody-and-control-form-ccf.pdf
  5. Mandatory Guidelines for Federal Workplace Drug Testing Programs, Urine. 88 Fed Reg 70768-70810. Published October 12, 2023. Effective February 1, 2024. Accessed September 27, 2026. https://www.govinfo.gov/content/pkg/FR-2023-10-12/pdf/2023-21734.pdf

Watch one

Read each decision and its explanation.

A 24-hour urine for protein arrives from Edwin Reade, 63, whose last 24-hour protein was 480 mg/24 h. The requisition shows 07:00 to 07:00, and he is not fluid-restricted.

Can a 24-hour protein excretion be reported from this collection?

TestResultReference intervalFlag
Urine protein9 mg/dL
Urine creatinine52 mg/dL

Specimen: Not measured on urine. 24-hour urine, 700 mL, 07:00 to 07:00

  1. Check the recorded times: 07:00 to 07:00, exactly 24 hours.

    A wrong interval changes every total that follows.

  2. Check the volume: 700 mL is low enough to raise concern about a missed void.

    An adult who drinks normally rarely passes as little as 700 mL in a day.

  3. Total creatinine = 52 mg/dL × 700 mL ÷ 100 = 364 mg, far below the 800 mg/day lower end expected for a man.

    Creatinine output is steady from day to day, so a low total indicates missing urine.

  4. Total protein = 9 mg/dL × 700 mL ÷ 100 = 63 mg, against 480 mg/24 h last time.

    The same calculation gives the protein total, which can be interpreted only when the collection is complete.

  5. Ask about missed voids through your procedure before looking for an analytical cause.

    The aliquot cannot show a missed void, so the patient's account is needed.

No. The collection holds 364 mg of creatinine, well under a man's daily output, so it is incomplete. The 63 mg protein total understates his excretion, and a new complete collection is needed.

Practice this skill

Your turn

Problem 1 of 3 · Hints available

A mid-collection void was accidentally discarded after a 24-hour collection had correctly started. What does this mean for the daily analyte excretion?

Incorrect. Aliquot volume shows only that the test can run. It does not show whether every void was saved.

Correct. The discarded urine contained analyte that the measured total no longer contains, and the aliquot cannot reveal the loss, so any excretion calculated from this collection understates the true value.

Incorrect. An estimated volume cannot restore the analyte in the discarded urine, so the calculated excretion stays unreliable.

Hint
  1. The analyte in the discarded urine was lost with it.
  2. Consider what the aliquot can show about urine that never reached the container.

Review Timed collections

Problem 2 of 3 · Hints available

In a federal workplace urine collection, which step on the Federal Custody and Control Form belongs to the donor?

Correct. The donor watches the collector seal both bottles, initials the tamper-evident seals, and signs the donor certification. The collector completes the remaining entries.

Incorrect. The collector measures the temperature within 4 minutes of receiving the specimen. A result outside 32 to 38 °C leads to a second collection under direct observation.

Incorrect. The HHS-certified laboratory or instrumented initial test facility records the primary seal condition when it receives the package.

Hint
  1. Three parties make entries on the form: the donor, the collector and the receiving facility.
  2. The donor's part happens at the table, right after the bottles are sealed.

Review Federal workplace drug testing

Problem 3 of 3 · On your own

Put these steps of a federal workplace urine collection in order, from the donor's specimen to the certified laboratory.

  1. The donor watches the bottles being sealed and initials both seals.
  2. The collector reads the specimen temperature within 4 minutes.
  3. The donor signs the donor certification on the Federal CCF.
  4. The certified laboratory records the receipt date and the primary seal's condition.
  5. The collector completes the form and ships the sealed package.
  6. The collector pours at least 30 mL into bottle A and at least 15 mL into bottle B.
Show the answer

The collector reads the specimen temperature within 4 minutes., The collector pours at least 30 mL into bottle A and at least 15 mL into bottle B., The donor watches the bottles being sealed and initials both seals., The donor signs the donor certification on the Federal CCF., The collector completes the form and ships the sealed package., The certified laboratory records the receipt date and the primary seal's condition.

The temperature is read first, within 4 minutes of receiving the specimen. The split into bottles A and B follows, then sealing in the donor's sight, the donor's initials and certification, the collector's entries and shipment, and finally the laboratory's receipt entry. Each entry links the sealed bottles to the next custodian.

Review Federal workplace drug testing

Use it

Read the case evidence, then make each decision. The step is complete without it.

  • Two specimens reach your laboratory's receiving desk. The laboratory is HHS-certified for federal workplace testing.
  • First, a 24-hour urine for protein from Rosalind Spindler, 61. On the requisition she wrote that she started at 08:00 Tuesday by saving that morning's first void, and ended at 08:00 Wednesday with a final void.
  • The container holds 1,650 mL.
  • Second, a sealed federal workplace package with its Federal CCF, handed over by a courier.
TestResultReference intervalFlag
Urine protein32 mg/dL

Specimen: Not measured on urine. 24-hour urine, 1,650 mL, 08:00 to 08:00, start void saved

Decision 1 of 3

The protein total is 32 mg/dL × 1,650 mL ÷ 100 = 528 mg. What does the saved 08:00 void do to it?

The 08:00 void contains urine formed overnight, before the interval began. Its protein adds to the 24-hour total.

A normal volume does not show when the urine was formed. The start void adds protein from outside the interval.

Calculated a daily excretion from an incomplete collection

A discarded void loses analyte that testing the aliquot cannot detect, so calculated excretion is falsely low. Including urine formed before the start time falsely raises it. A low volume, such as 700 mL from an adult who is not fluid-restricted, raises concern for an incomplete collection.

A lost void lowers the total. This collection has extra urine, which raises it.

Review Timed collections

Decision 2 of 3

What do you do with the 24-hour protein?

The comment does not show how much of the 528 mg came from the extra void.

The first void's volume and protein are unknown. Any subtraction would be an estimate reported as a measurement.

Only a collection over the exact interval gives a true daily excretion. Record the saved start void as the reason.

A plausible number can still include urine from outside the interval. The requisition shows that it does.

Calculated a daily excretion from an incomplete collection

A discarded void loses analyte that testing the aliquot cannot detect, so calculated excretion is falsely low. Including urine formed before the start time falsely raises it. A low volume, such as 700 mL from an adult who is not fluid-restricted, raises concern for an incomplete collection.

Review Timed collections

Decision 3 of 3

How do you receive the federal package?

The receiving facility inspects the primary seal. The custody entry records what the receiver observed.

These entries continue the custody record from the collector to the laboratory, so the result can be tied to that sealed specimen.

Routine handling leaves a gap in the custody record, and the result can no longer be shown to belong to the sealed specimen.

Used routine handling without the required custody record

Each federal workplace specimen is accompanied by a Federal Custody and Control Form that records each transfer and the seal condition at receipt. Handling one like a routine clinical urine breaks the chain of custody, and the result can no longer be linked to that sealed specimen.

Review Federal workplace drug testing

The 24-hour urine turns on the patient's note that she saved the 08:00 start void. The volume was normal, and only the collection record showed that the total included urine from before the interval. For the federal package, the custody record defines what counts as received.

For reference

Sources checked